The electrical transport properties of Mn doped InAs single crystal (InAs:Mn) were determined from temperature-dependent Hall effect measurements over the temperature range of 77-300 K. Both samples were found to be p-type attributed to Mn acceptors randomly substituting for indium lattice sites. The sample with relatively higher doping concentration exhibits characteristics with nearest-neighbor hopping conductance (NNH) in impurity band below 200 K. The ionization energy of the Mn acceptor in InAs is determined to be 27 meV from the analysis of PL spectrum of the lightly doped sample. It is determined from the value of ionization energy that the localized radius a(0) of the manganese acceptor is 17 angstrom.

Undoped, S-doped and Fe-doped 4 inch diameter (100) InP single crystals with average dislocation etch pit density less than 5000 cm-2 have been grown by using high pressure vertical temperature gradient Freeze (VGF) method.A multiple points X-ray double crystal diffraction measurement across the 4 inch wafer indicates a full width at half maximum (FWHM) around 30 arcsec with uniform distribution of the rocking curves.Due to the low temperature gradient during the VGF growth process, the possibility of twin generation is quite high compared to that of liquid encapsulated growth process (LEC).However, the orientation of the crystal main body is still (100) direction after the twin formation on the VGF-InP crystal ingots.In this case, a large quantity of (100) single crystal wafers with diameter of 2 inch, 3 inch and 4 inch can be sliced from the ingot.Since the effective segregation coefficient is very low for Fe, polycrystal growth caused by composition super cooling of Fe-doped InP VGF is found frequently.The single crystal yield of the Fe-InP VGF growth can be increased significantly by strictly control the Fe doping quantity and the temperature gradient.Electrical property, dislocation density and its distribution, lattice perfection of the VGF-InP single crystals have been investigated.

Undoped and Te-doped 4 inch diameter (100) GaSb single crystals in 5-8 kg weight have been grown by using liquid encapsulated Czochralski (LEC) and substrate wafer have been prepared.By optimizing the thermal field, single crystal yield as high as 80% have been achieved.Dislocation etch pit density (EPD) of the wafer is less than 500 cm-2 and its X-ray diffraction rocking curves has a full width at half maximum (FWHM) around 29 arcse, indicating a high lattice perfection.The wafer has good electrical uniformity, benefiting from the flat solid-liquid interface during the single crystal growth process.Epi-ready 4 inch GaSb substrate wafer with good flatness and low surface roughness has been prepared.N type GaSb wafer with good near infrared transmittance has been prepared by controlling the native acceptor concentration and doping concentration.

Te-doped GaSb single crystals are studied by measuring Hall effect, infrared (IR) transmission and photoluminescence (PL) spectra. It is found that the n-type GaSb with IR transmittance can be obtained as high as 60% by the critical control of the Te-doping concentration and electrical compensation. The concentration of the native acceptor-associated defects is apparently low in the Te-doped GaSb compared with those in undoped and heavily Te-doped GaSb. The mechanism for the high IR transmittance is analyzed by considering the defect-involved optical absorption process.

The surface quality of HCl-etched and ammonium sulfide [(NH4)2S]-based treated bulk n-GaSb(100) were compared using x-ray photoelectron spectroscopy (XPS) and TOF-SIMS. It has been found that native oxides present on the GaSb surface are more effectively removed when etched with concentrated HCl solution. With additional [(NH4)2SO4+S] substances or hydrogen ions in the passivation solution, the treated samples displayed significant reduction of native oxides and formation of the sulfides compared with pure (NH4)2S solution. The treated samples also result in a noteworthy improvement in the current–voltage (I–V) characteristics of Au/n-GaSb Schottky contacts, as evidenced by the lower ideality factor (n), higher barrier height (Φb) and higher rectification ratio at ±0.2V. The I–V measurement provided definitive confirmation of XPS and TOF-SIMS results, establishing the need for less alkaline solution for greater passivation stability.

The surface chemical properties of gallium antimonide (GaSb) after ammonium sulfide ((NH4)2S) solution passivation have been studied by X-ray photoelectron spectroscopy (XPS), time of flight secondary ion mass spectroscopy (TOF-SIMS) and I–V measurement. An advantage of neutral (NH4)2S + S solution over pure (NH4)2S solution and alkaline (NH4)2S + S solution has been found in the ability to passivate the GaSb surface by contrast and comparison. It has been found that alkaline (NH4)2S + S solution passivation effectively removes oxides of the GaSb surface and forms sulfide products to improve device performance. TOF-SIMS complementally demonstrates that pure (NH4)2S passivation did form sulfide products, which are too soluble to really exist. The lowest roughness determined using a 3D optical profilometer and the highest improved SBD quality proved that neutral (NH4)2S + S solution passivation worked much better in improving the surface properties of GaSb.

对相同条件下制备的不同晶向的锑化镓抛光晶片表面化学组分进行了XPS测试比较,结果表明(110)GaSb晶片表面的氧化程度最为严重,表面极为粗糙;有极性的(111)GaSb晶面由于Ga-Sb价键存在于衬底内部,反而氧化程度较低,表面较光滑.分析比较了GaSb晶面表面化学组分与形貌的关系.

Residual impurities and contamination on semi-insulating (SI) InP wafers are detrimental for epitaxial growth and device performance, especially because residual silicon on an SI-InP wafer surface is electrically active and generates an n-type conduction layer at the interface between the epilayer and the InP substrate. In order to reduce the concentration of Si and improve surface quality, the authors investigate a wet-chemical cleaning process for ready-to-use InP substrates. A novel and practical cleaning process was developed by adding an alkaline solution to the conventional acidic cleaning process. Time-of-flight secondary mass spectrometry, a very powerful analysis technique to characterize surfaces and investigate any organic and inorganic contamination present on the InP surface, was used after the samples were etched under different cleaning processes. The results show that the novel etching process effectively reduces the Si contamination.