One-dimensional (1D) nanorods (NRs) of multifunctional ZnO have immense applications while suffering from the drawbacks of surface adsorbed species modifying the optical properties as well as constraints in extrinsic impurity doping due to limited dopant solubility. This study reveals tuning the intrinsic defects in 1D ZnO NRs subjected to post-growth annealing in Zn-rich ambience to modify the structural, optical and electrical characteristics in a controlled way. Accumulation of Zn species from the bare Zn film to the NRs' surface reacts with the surface-adsorbed oxygen, forming a new coaxial ZnO layer as confirmed by field emission scanning electron microscopy and high-resolution transmission electron microscopy. Under low oxygen chemical potential, oxygen atoms can diffuse outward to maintain charge neutrality and thermodynamic equilibrium, resulting in the creation of oxygen vacancies (VO) and Zinc interstitials (Zni) in the NRs as Zn thickness increases as observed from the X-ray photoelectron spectroscopy. Raman spectroscopy confirms defect-related and disorder-induced multiphonon modes in the Zn-annealed NRs. The photoluminescence spectra further support a significant increase in VO concentration, consistent with the enhanced green emission. An enhancement in the carrier concentration and mobility have been observed by Hall measurements in the Zn-annealed samples, and is attributed to an increase in the donor-related defects. Temperature-dependent resistivity measurements (11-300 K) further reveal the activation energy of the pristine ZnO NRs sample is approximately 53.2 meV, which gradually decreases to 18.1 meV for the highest Zn annealed sample due to the hopping of the carriers in the broadened of Zni related defect states just below the conduction band minima.

Stoichiometric defects in ZnO intricately modulate its photophysical properties. In this study, temperature-dependent photoconductivity measurements are employed as a powerful tool to probe the defect-mediated carrier dynamics in non-stoichiometric ZnO1-s thin films deposited via RF magnetron sputtering with only Ar (ZAR) and Ar+O2 (ZARXOY). The ZARXOY films show significantly reduced dark current, faster photoresponse, and enhanced UV photosensitivity compared to ZAR. The photocurrent transients under successive excitations at room and low temperatures intriguingly reveal carrier trapping phenomena and associated energy levels. The traps at and within 1.77-2.07 eV below the conduction band predominant in ZAR are probably attributed to oxygen vacancies, as corroborated by XPS and PL. While traps within 2.07-2.48 eV below the conduction band, associated with zinc vacancy defects, prevail in ZARXOY. Interestingly, at lower temperatures, the photocurrent is diminished for ZAR due to prominent carrier entrapment and defect-induced scattering, whereas photocurrent is enhanced for ZARXOY films. Prolonged carrier relaxation and higher activation energy in ZAR indicate persistent photoconductivity due to abundant traps, whereas ZARXOY exhibits faster relaxation and minimal persistency. These findings underscore the role of photoconductivity in probing intrinsic defects to optimize optoelectronic properties of ZnO1-s, advancing high-performance UV photodetectors and devices.

Deciphering defect-governed photocarrier dynamics in ultrawide bandgap beta-Ga2O3 is imperative for tailoring its functionalities in advanced optoelectronic architectures owing to its intrinsic ultraviolet transparency and high critical electric field. In this study, pulsed laser-deposited beta-Ga2O3 thin films grown with various oxygen partial pressures (1-50 Pascal) lead to a modulation of the sub-band gap defects' distribution. The films crystallized in the monoclinic beta-Ga2O3 phase show improvement in the crystal quality as the oxygen pressure increases. Room-temperature photoconductivity shows a photo-to-dark current ratio of similar to 4 & times; 10 & sup2;, responsivity of 50 mA/W, and fast rise-decay dynamics, making the films suitable for applications such as solar blind short-range secure space communications. The film deposited under lower oxygen pressure displays a sublinear power-law dependence, attributed to trap-assisted carrier dynamics and persistence of the photocarriers, while the film grown at higher oxygen pressure shows an almost linear response, reflecting intrinsic band-to-band excitation with negligible defects' role. The stable and repeatable photoresponse over multiple cycles confirms improved reliability and reproducibility of the films. The unprecedented temperature-dependent photocurrent measurements (12-300 K) reveal a rich variety of defect-dominated transport mechanisms operating across distinct temperature regimes. The analysis demonstrates a sequential transition from trap-mediated Efros-Shklovskii and Mott variable-range hopping (VRH) to nearest-neighbour hopping and finally to thermally activated band conduction. Notably, each film exhibits these conduction processes over different characteristic temperature intervals, depending on the oxygen partial pressure used during growth. For the film deposited at 1 Pa (GO-1), VRH transport dominates below 50 K. In contrast, the film grown at 50 Pa (GO-50) retains VRH behaviour up to nearly 200 K. Additionally, thermal activation of recombination centres induces photocurrent quenching above similar to 100 K in GO-1 and above similar to 260 K in GO-40. These insights emphasize the fundamental significance of defect-carrier interactions in tailoring next-generation deep-UV and cryogenic optoelectronic devices.

To date, transition metal dichalcogenides (TMDCs) are mostly explored as 2D semiconducting materials due to their distinctive properties as compared to their bulk counterparts while similar research focus on post-transition metal dichalcogenides (PTMDCs) is still in infancy. Here, we demonstrate an interesting contrast between photocarrier dynamics in quasi-2D van der Waals TlGaS2, revealed through a comparative study of single-crystal and exfoliated microflake. The single crystal exhibits pronounced temperature-sensitive spectral features indicative of strong carrier-phonon coupling and delivers a maximum responsivity of 5 mA/W under 490 nm illumination. In contrast, the microflake shows faster, weakly temperature-dependent carrier relaxation and narrowband blue-UV selectivity. Remarkably, the microflake demonstrates an enhanced responsivity of 32.1 mA/W, with a negligible response to green and red light, revealing TlGaS2 single crystals as visible photodetectors with optically tunable switching, while the microflake as a low-power, blue-UV selective, temperature-robust optical-digital conversion system. Most importantly, this work provides fundamental insight into temperature-dependent carrier transport and dimensionality-driven photocarrier dynamics in quasi-2D PTMDCs.

Engineering defects via controlled doping is not only pivotal but also tricky in tuning the carrier transport mechanisms of transparent conducting films. In this study, defects have been systematically introduced by co-doping with Ti via ion implantation in Al doped ZnO (AZO) films, focusing on both electrical and magneto-electric transport mechanisms. Room temperature (RT) Hall measurement shows a gradual increase in the carrier concentration and a decrease in the mobility with an increase in the ion fluences. Notably, the resistivities of the implanted AZO films up to a fluence of 5 x 10(15) ions/cm(2) exhibit metallic behaviour at RT but undergo a metal to semiconductor transition (MST) at well below RT. Detailed analyses of the transport properties, utilizing quantum corrections, reveal that electron-electron interaction plays dominant role ahead of weak localization in both AZO films, with and without implantation in determining the carrier transport process below the transition temperature. The gradual increase in the MST transition temperature with ion fluences can be primarily attributed to an enhanced scattering of electrons, which allows quantum interference effects to manifest at higher temperatures. The observed negative magnetoresistance is well described by the semiempirical model of Khosla and Fischer, which involves conduction electron scattering at defect induced localized magnetic moments. The defect induced transition from weak to strong carrier localization and modulated magnetoresistance in Ti implanted Al Doped ZnO films have also been supported by theoretical simulations estimating point defect concentrations, as well as experimental Raman and X-ray photoelectron spectroscopy data analyses.

Ternary post transition metal chalcogenides are gaining significant interest for their potential optoelectronic applications due to the dual bandgap and highly anisotropic nature. This study utilizes simultaneous vibrational and mu-photoluminescence (PL) spectroscopy to gain understanding of how single-crystalline as well as exfoliated TlGaS2 behave as the temperature and layer number change. Unprecedently, observed Raman peaks may be assigned to reported group theoretically calculated vibrational modes, which reveal softening and a systematic change in anharmonic characteristics with an increasing temperature. The sub-bandgap electronic transitions exhibit distinct temperature-dependent radiative recombination behaviors owing to donor-acceptor pair (A band) and trapped bound excitons (XB). The exfoliated flakes reveal an anomalous frequency shift in the Raman modes in contrast to transition metal chalcogenides and almost unaltered mu-PL emission intensity as the thickness is reduced exploring possibilities of advanced semiconductor technologies.

The diverse nature of optoelectronic properties of few-layer or monolayer MoS2 is generally dominated by A and B excitons. Occasionally, strong Coulombic interactions within the 2D monolayer led to the creation of hydrogen-like Rydberg states of excitons in MoS2 similar to other 2D monolayers. In this paper, a simple process is used to convert trilayer MoS2 films to a monolayer by introducing H2 gas during chemical vapor deposition. Remarkably, alongside the usual A, B excitons, and A- trion, the appearance of the Rydberg states is evidenced by photoluminescence spectra even at room temperature; also, there is an increase in their areal percentage with an increase in H2 content. The s-type excited Rydberg states up to the fourth order (n = 5) and third order (n = 4) of A and B excitons, respectively, have been probed from the photoluminescence spectra at 93 K. Unprecedentedly, the first-order derivative of room-temperature photocurrent spectrum reveals the Rydberg states concurrently and elaboratively. Furthermore, the large-area MoS2 films exhibit photoresponse in a broad UV to visible region with excellent photosensitivity (∼102) toward both UV and visible lights. Not only does this provide a profound understanding of the excitonic Rydberg states but also highlights the considerable potential of large-area monolayer MoS2 overcoming the difficulty of tiny flake-related 2D device endeavors.

We investigated here the effect of defects on the structural and photophysical properties of TiO2 films implanted with Li ions with fluences from 1 × 1014 to 1 × 1015 ions/cm2. All the films showed tetragonal anatase structure but higher angle shift of the (101) peak of implanted films confirms Li doping in Ti site. This result is also supported by our X-Ray photoelectron spectroscopy study. The results also indicated that with an increase in Li ion fluence, formation of defects like oxygen vacancy and/or Ti3+ species increases in implanted samples. This is also supported by theoretical “stopping and range of ions in matter” (SRIM) simulations. The introduction of oxygen vacancy-Ti3+ defects act as recombination centers which gives rise to significant change in emission properties and decrease the photoresponse properties of the TiO2 films after Li implantation.

The characteristics of 2D layered MoS2 film are highly dependent on the substrate it is grown on which leaves us privileged to achieve unique and tunable properties. In this study, trilayer MoS2 films have been grown on fused quartz, crystalline quartz (z-cut), sapphire (0001), and silicon (100) substrates. MoS2 film grows as freestanding on amorphous fused quartz, while it experiences an in-plane tensile strain on the sapphire and silicon. Unprecedentedly we show that due to a large mismatch in the lattice parameter as well as in the thermal expansion coefficient, MoS2 grows with a significant compressive strain both along both in-plane on the crystalline quartz. The developed strain causes an alteration in its electronic structure, causing a 30 meV blue shift in the photoluminescence peak and an increased band gap in addition to fewer sulphur vacancies. Comparatively, the film on sapphire having tensile strain along the in-plane exhibits more sulphur vacancies increasing the electron density. The photoresponse time, photosensitivity, and charge separation distinctly vary for the MoS2 films depending on the substrates. This study underscores the influence of substrate on MoS2 film opening further research scopes on tunable properties owing to 2D layer-substrate interactions.

Amidst the rapid advancement of flexible and transparent optoelectronic devices, the oxide/metal/oxide (O/M/O) trilayer structure has been considered to be a potential transparent conducting electrode (TCE) because of its superior stability and better durability as compared to single-layered TCEs or metallic films. In this study, we report an ultrathin sputter-deposited SnO2/Cu/SnO(2 )trilayer TCE with excellent electrical and optical properties appropriate for flexible and transparent optoelectronic devices. All of the deposited TCE films are almost amorphous in nature with an excellent smooth surface texture, as evident from the X-ray diffraction and atomic force microscopy studies. The X-ray photoelectron spectroscopy study reveals that Cu remains in the elemental state, sandwiched between two oxide layers. The lowest resistivity value of 1.59 x 10(-4) Omegacm along with the highest figure of merit value of around 1.37 x 10(-3) Omega(-1) have been obtained for a 23 nm (10/3/10) trilayer. The enhanced conductivity in the films primarily results from carrier injection from the Cu layer to the oxide layer. A ZnO-based flexible and all-transparent ultraviolet photodetecting device on polyethylene terephthalate substrates featuring optimized O/M/O (10/3/10) electrodes achieves responsivity and detectivity values of 0.33 mA/W and 3.06 x 10(10) Jones, respectively. The device shows a remarkably stable photoresponse under flat as well as various bend conditions. Therefore, this study provides potential ways for fabricating high-quality O/M/O TCEs across a broader spectrum of flexible and transparent optoelectronic devices.

A significant development toward semiconductor-based electronic devices is based on the electric and magneto-electric control of the transport properties of the charge carriers. This study unprecedentedly investigates the Ti implantation and thereafter the effect of structural defects on the electrical and magneto-electric transport properties of Ti-implanted RF-sputtered ZnO thin films. Theoretical stopping and range of ions in matter simulations along with the experimental structural and elemental studies reveal that Ti ion implantation generates a significant amount of oxygen vacancy (VO) defects apart from Ti-related impurities in post-implantation annealed films. The film implanted with 8 × 1015 ions/cm2 (TZO815) exhibits the lowest resistivity (4.68 × 10−3 Ω cm) and the highest carrier concentration (6.61 × 1020 cm−3) values. Resistivity measurements over a temperature range of 5-300K indicate semiconducting behavior for all the films implanted up to fluences of 5 × 1015 ions/cm2 identified with a grain boundary dominated thermally activated band, nearest neighbor hopping, and Mott and Efros–Shklovskii (ES) variable range hopping conduction mechanisms at various temperature intervals. Notably, the gradual decrease in both Mott and ES hopping ranges following Ti implantation indicates the formation of more localized states. Interestingly, the TZO815 film exhibits metal-semiconductor transition around 220 K, suggesting the formation of a degenerate band within the ZnO conduction band upon Ti implantation. Remarkably, the magnetoresistance results align with a semiempirical formula proposed by Khosla and Fischer, indicating that a negative magneto resistance in the TZO thin films is attributed to the spin-dependent scattering of conduction electrons by the localized magnetic moments induced mainly by the implantation induced VO defects.

One-dimensional ZnO exhibits fascinating electrical and optical properties enabling remarkable performance in photonics, sensors, optics and photovoltaic devices. Stopping and Range of Ions in Matter (SRIM) simulations for Ti ion implantation into ZnO nanorods (NRs) at varying fluences (1 x 1014 to 5 x 1015 ions/cm2) at 100 keV results in an electron to nuclear energy loss ratio (Se/Sn) of 0.22, with maximum Ti ion occurrence and point defects within 100 nm along the NRs. Theoretical predictions align with experimental results especially of Raman scattering, X-ray photoelectron spectroscopy, and photoluminescence confirming an increase in the structural point defects with escalating Ti fluence. The pristine ZnO NRs initially exhibit yellow-orange photoluminescence emission. Following implantation, this emission transforms into green, which is due to zinc vacancies. The agreement between theoretical simulations and experimental results affirms the validity of our investigation into the formation and progression of point defects in Ti-implanted ZnO NRs.

Understanding the carrier transport mechanism of transparent conducting oxides is crucial for its application in optoelectronic devices. Although, electrical transport mechanisms of various trivalent cation doped ZnO films have been reported adequately, a substantial study is needed to understand the transport mechanism in ZnO doped with higher valence (> +3) dopants. Unlike Al, In and Ga doped ZnO where metalinsulator transition is commonly observed, in this study, the crossover amongst band and various hopping mechanisms has been observed in the temperature range of 300-10 K in Mo doped ZnO films deposited at various substrate temperatures. All the films show electrons as the majority charge carriers and notably, the film deposited at 573 K shows the highest conductivity value of 167.22 (ohm.cm)-1. In-depth analyses of the conduction mechanism reveal grain boundary scattering dominated band conduction at and not far below the room temperature, which is shifted towards nearest neighbor hopping (NNH), and then to Mott variable range hopping (VRH) type of conductions as the temperature is decreased further. Unfamiliarly, a modified Efros-Shklovskii (ES) VRH type of conduction mechanism is shown to prevail in the lowest measured temperature range (similar to 30-10 K). Unprecedentedly, it is demonstrated here that the activation energies for various conduction mechanisms are higher at lower vacuum condition (similar to 10-1 mbar) as compared to those measured at higher vacuum condition (similar to 10-3 mbar) implying an added role of the surface traps in the charge transport process. The temperature dependent conductivity and X-ray photoelectron spectroscopy (XPS) studies proclaim that the film deposited at 573 K possess fewer defects related disorder for carrier localization as compared to the films deposited at 523 K and 698 K.(c) 2023 Elsevier B.V. All rights reserved.

A high-performance broadband photodetector has at-tracted significant attention due to its wide range of applications. We report an n+-ZnO/n-Si isotype heterojunction by depositing ZnO nanorods followed by a ZnO thin film on an n-type undoped Si wafer for detecting a broad wavelength from 300 to 940 nm with a high speed under reverse as well as zero bias conditions. Under 1.5 V reverse and zero bias, the device provides responsivity values up to similar to 200 and similar to 13 mA/W respectively. Under self-bias, the n+-ZnO/n-Si heterojunction exhibits up to 1.2 x 103 photosensitivity. The n+-ZnO/n-Si hetero-junction can detect power as low as 10-12 mu W/cm2. A photoresponse up to 2 kHz modulated illuminations has been measured, and the ultrafast n+-ZnO/n-Si heterojunction provides a stable and rapid photoresponse with a response time in the 60-120 mu s range. The n+-ZnO/n-Si heterojunction exhibits a -3 dB cutoff frequency of >2000 and 1100 Hz under reverse and zero bias, respectively. Therefore, we unprecedentedly demonstrate an n+-ZnO/n-Si isotype heterojunction as a potential candidate for detecting light in a broad ultraviolet to infrared region with a very high speed and >1 kHz frequency bandwidth as well.

In this study, we have demonstrated the interaction ofan ultrathinZn surface passivation layer with a room temperature (RT)-depositedAl-doped ZnO (AZO) film, leading to highly improved electrical transportproperties. The resistivity of the AZO film increases monotonicallywith time in ambient conditions (from 0.02 to 0.33 & omega;& BULL;cm),while overlaying a 4 nm Zn layer on AZO film stabilizes the resistivityto a value of 4.56 x 10(-3) & omega;& BULL;cm,which decreases to a value of 2.40 x 10(-3) & omega;& BULL;cmfor a 5.3 nm Zn overlayer. The remarkable enhancement in the electricalstability and the conductivity value is attributed to a probable diffusionof Zn species into the AZO films, passivating Zn vacancy (V-Zn) and forming Zn interstitial (Zn-i), Zn-i-V-O donor complexes supported by RT Raman and X-ray photoelectronspectroscopy studies. Temperature-dependent resistivity measurementreveals the semiconducting behavior of the AZO films with 4 and 6nm Zn overlayer, where the transport process is governed by thermallyactivated band conduction at and below RT (up to & SIM;247 K), followedby nearest-neighbor hopping and Mott variable range hopping mechanismsas the temperature goes down. The 5.3 nm Zn-coated AZO film showsmetallic behavior at RT and a metal to semiconductor transition & SIM;220K deviating from the Boltzmann conduction process due to electron-electroninteraction phenomena.

Here, we report a stable p-type conductivity in aqueous chemically grown ZnO nanorods array films coimplanted with N and Li ions. We have successfully achieved p-type conductivity, attaining a hole concentration as high as 8.97 x 1018 cm-3 and a mobility of 0.92 cm2.V- 1.s- 1 by co-implanting N and Li ions at a fluence of 5 x 1014 ions/cm2 for each ion. X-ray photoelectron spectroscopy analysis reveals the formation of NO, LiZn acceptors, and Lii-NO complexes. Furthermore, room temperature photoluminescence and SRIM simulation results confirm the presence of VZn. The formation of Lii-NO complex helps LiZn, VZn, and NO acceptors to actively participate in p-type conduction process. A detailed photoluminescence and Raman spectroscopy analyses together with simulation results reveal that, as the co-implantation fluence increases, excess Lii and implantationinduced structural disorders are produced, resulting in a decrease in the hole concentration. Our study showcases the potential benefits of developing a stable p-type component in ZnO-based electronic devices.

Zinc oxide (ZnO) offers a major disadvantage of asymmetry doping in terms of reliability, stability, and reproducibility of p-type doping, which is the main hindrance in realization of optoelectronic devices. The problem is even more complicated due to formation of various native defects in unintentionally doped n-type ZnO. The realization of p-type conductivity in doped ZnO requires an in-depth understanding of the formation of an effective shallow acceptor, as well as donor-acceptor compensation. Photophysical properties such as photoconductivity along with photoluminescence (PL) studies have unprecedentedly and effectively been utilized in this work to monitor the evolution of various in-gap defects. Phosphorus (P) doped ZnO thin films have been grown by RF magnetron sputtering under various Ar to O2 gas ratios to investigate the effect of O2 on the donor-acceptor compensation by comprehensive photoconductivity measurements supported by the PL studies. Initial elemental analyses indicate presence of abundant zinc vacancies (VZn) in O-rich ambience. The results predict that P sits in the zinc (Zn) site rather than the oxygen (O) site causing the formation of PZn–2VZn acceptor-like defects, which compensates the donor defects in P doped ZnO films. Photocurrent spectra uniquely reveal presence of more oxygen vacancies (VO) defects states in lower O2 flow, which gets compensated with an increase in the O2 flow. Successive photocurrent transients indicate probable presence of more VO in the films grown with lower O2 flow and more VZn in higher O2 flow. Overall the photosensitivity measurements clearly present that O-rich ambience expedites the formation of acceptor defects which are compensated, thereby lowering the dark current and enhancing the ultraviolet photosensitivity.

In this work, we present an in-depth comprehensive study on the evolution of various point defects in 100 keV lithium (Li) ion implanted ZnO nanorods (NRs) with varying the fluences from 1×1014 to 7×1015 ions/cm2. The analyses of x-ray photoelectron spectroscopy results validate the incorporation of Li1+ at Zn2+ site forming LiZn acceptors in the implanted NRs. Detailed x-ray diffractometry results indicate that the structural disorders increase with an increase in the Li ion fluence. Raman scattering analyses also gives a clear indication of an increase in the lattice disorder as well as formation of oxygen vacancy in the ZnO NRs due to Li ion implantation. Again, the I-V measurement indicates highly resistive NRs after implantation due to probable formation of both the acceptors and the various implantation-induced defects in the Li implanted NRs. A clear correlation between zinc vacancy (VZn) and the green photoluminescence emission in the implanted ZnO NRs has been confirmed. However, a suppression of the green emission has been observed at higher fluences, which is possibly due to an apparent decrease in the VZn concentration. The theoretical Monte Carlo simulation code named Stopping and Range of Ions in Matter well explains the experimental observations in the context of energy lose by the implanted Li ions and the distribution of intrinsic point defects in the target ZnO. The consistency between our various experimental and the theoretical simulation results confirms our understandings on the formation and evolution of various point defects in the implanted ZnO NRs making this study a benchmark for understanding the defects owing to group I ion implantation in ZnO NRs.

Noble metal-TiO2 composite films attract great attention because of the extension of its spectral absorption in the visible range due to surface plasmon resonance. Among them, Ag-TiO2 composite is considered to be an ideal candidate for the visible light photosensitivity because of narrow energy distribution of plasmonic hot electrons in Ag and the high density of states in the TiO2 conduction band. Here, we report high broad band photosensitivity from ultraviolet (UV) to visible wavelength of sol-gel grown TiO2 film decorated with Ag nanoparticles (NPs) in a simple planar photoconductive geometry. In addition to UV light, Ag NPs-TiO2 composite film (for 1 nm Ag) shows very high photosensitivity values of ∼105 and ∼104 and responsivity values of 0.1 A/W and 7×10−3 A/W at 10 V bias for 680 nm and 550 nm illuminations respectively while pristine TiO2 show photosensitivity values of 6×102 and 3.3×102 and responsivity values of 2.4×10−4 A/W and 6.6×10−5 A/W for both the visible illuminations. A highly enhanced broad band photosensitivity due to transfer of plasmonically generated hot electrons from Ag to TiO2 is quite interesting without having any device fabricated. The photosensitivity values for Ag NPs for 3 nm and 6 nm layer thicknesses on TiO2 decrease because of coalescence of metal NPs on surface which acts as scattering center and/or light shielding.

Carrier (electron) compensation is an important issue in impurity (donor) doped ZnO thin films, which must be understood to achieve the desired electrical conductivity. Unprecedentedly, using trivalent Al, tetravalent Ti, and pentavalent Vanadium, (the atomic symbol is not used to avoid confusion with the conventional vacancy symbol) metal ion doping in ZnO thin films while keeping all the growth and annealing parameters similar, we demonstrate that donor–acceptor (D-A) compensation in the doped film is influenced largely by the dopant valence. Hall data show a drastic decrease in the conductivity and carrier concentration values indicating progressively more D-A compensation as the dopant valence increases. Post-growth annealing in special ambient recovers trapped free carriers due to dopants’ activation. The activation of the dopants due to annealing in Ar + 10% H2 + excess Zn ambient is far more than that happened in only Ar + 10% H2 ambient. To support this, we further discuss the dark and photo-Hall electrical transport data of the as-grown and annealed films measured under sub-bandgap photo-excitations to release the electrons from the acceptor-like complexes.