Using gallium nitride (GaN) technology, this article reports a NOT gate operating up to 800 C-degrees, and an 11-stage ring oscillator (RO) operating up to 600 C-degrees in a nitrogen environment. Each NOT gate contains two stages-an input resistor-transistor logic stage and an output level shifter stage. The transistors feature threshold voltages of around -2 V at 25 C-degrees and around -3 V at 800 C-degrees. The ON-state current density decreased from 392mA/mm at 25 C-degrees to 70mA/mm at 800 C-degrees under gate-to-source voltage of 5 V and drain-to-source voltage of 10V. With the same RO circuit topology, the GaN technology demonstrated performance advantages over the silicon carbide (SiC) technology. The performance and operating temperature of the RO are currently limited by the breakdown of the intermetal dielectric, which can be mitigated by a thicker or higher quality dielectric.

Molybdenum disulfide (MoS2), a prominent member of the transition metal dichalcogenide family, stands out for its unique electronic and optical properties. To date, it is not well understood how doping works with distinct epitaxial layers to metal deposition. We investigate the charge doping effects of Bi and Au on MoS2 using Raman spectroscopy and transport measurements with Bi contacts, analyzing how doping influences epilayer growth and the electrical characteristics of coalesced monolayer (1L) and bilayer (2L) MoS2. We observe that coalesced 1L MoS2 provides a surface conducive to homogeneous doping, while regions with 2L MoS2 exhibit almost no signature for doping but improved device performance due to its enhanced carrier density. Specifically, our results show that field-effect transistors with Bi-contacted 2L MoS2 channels offer approximately 5x higher current density, 1.8x lower contact resistance (R-C), and 2x greater field-effect mobility compared to 1L channels. However, 1L MoS2 retains a superior on/off current ratio, exceeding 10(8), while the on/off ratio for 2L MoS2 is approximately 10(6). The findings shed light on the interplay between epitaxial layers and metal deposition, offering valuable insights into tailoring MoS2 devices to meet the demands of advanced electronic applications for enhanced performance and functionality.

The Au-free Ti/TaSi2/Ti/Pt ohmic contact to AlGaN/GaN was designed and tested at temperatures from 25 to 800 degrees C in air and nitrogen. As-fabricated contacts had contact resistance (RcW) <1 Omega mm at room temperature and remained ohmic at operating temperature 800 degrees C after being held for 1 h in either environment. For contacts tested in nitrogen, RcW measured at 800 degrees C was 3.75 Omega mm, and much of the increase in resistance upon first heating can be attributed to the increase in the semiconductor sheet resistance. After 1 h aging in air at 800 degrees C, RcW rose to 4.55 Omega mm before the contacts were cooled to room temperature. The contacts tested in air had a contact resistance of 3.17 Omega mm when measured initially at 800 degrees C, and RcW rose to 6.88 Omega mm by the end of 1 h. All contacts remained ohmic after they were cooled to room temperature, albeit with some permanent increase in resistance, particularly in the contacts held in air. Materials characterization including cross-sectional field emission scanning electron microscopy, energy dispersive spectroscopy, and x-ray photoelectron spectroscopy were performed to understand interlayer diffusion and gain greater insight into the remarkable stability of the contacts.

Edge contacts offer strong bonding and the potential for lower specific contact resistance to two-dimensional (2D) chalcogenide semiconductors, albeit to a very small area, and they are friendlier to scaling compared to top contacts. Physical vapor deposition (PVD) techniques are often used to fabricate contacts to 2D semiconductors and other electronic devices. However, PVD processes are not as easily scalable for edge contact manufacturing. In this work, we have studied thermal atomic layer deposition (ALD) of TiS 2 using tetrakis (dimethylamido) titanium and hydrogen sulfide for forming uniform and conformal edge contacts on single-layer MoS 2 . Characterization of the TiS 2 was performed using Raman spectroscopy, x-ray photoelectron spectroscopy, and scanning transmission electron microscopy to confirm the contact composition. A contact resistance of 130 Ω·mm was measured with a barrier height of 0.43 eV for the ALD-deposited edge contact TiS 2 /MoS 2 . Thermal ALD processes of the other possible edge contact materials to 2D semiconductors are being developed, including TiN. Furthermore, we have studied a scalable process for multi-tier edge contact fabrication using ALD, which would be more difficult to achieve via PVD, demonstrating the promising potential of ALD for forming electrical contacts to 2D semiconductors. The authors are grateful to NSF (ECCS 2227346), the NSF 2DCC MIP platform (DMR 2039351), and The Pennsylvania State University for support of this work. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

The ultrawide bandgap semiconductors AlN and AlN-rich AlGaN present new opportunities for devices, but the development of ohmic contacts remains a hurdle. This study addresses pre-metallization surface preparation and its impact on ohmic contact formation. The surfaces of n-AlxGa1-xN (0.67 < x < 0.83) and AlN were analyzed by X-ray photoelectron spectroscopy and atomic force microscopy before and after various surface preparations. A 10-min exposure to ultraviolet ozone, followed by a 1-min soak in 49% hydrofluoric acid, minimized carbon and oxygen on the surface most effectively but did not eliminate them completely. Nevertheless, using ultraviolet ozone followed by hydrofluoric acid-based treatments consistently resulted in a higher contact resistance than any of the other processes tested. Contact resistance measurements surprisingly revealed that omitting these steps resulted in the lowest specific contact resistance (9.3 x 10-5 Ω cm2), while use of ultraviolet ozone and hydrofluoric acid-based treatments resulted in highest contact resistances (2.9 x 10-4 Ω cm2). Transmission electron microscopy shows that even after such an acid treatment, an oxide is present at the metal/semiconductor interface in annealed contacts, and the possible role of the oxide is considered.

Sputtered tantalum silicide was studied as a diffusion barrier for Ti-based ohmic contacts to AlGaN/GaN heterostructures. The contacts had remarkable stability when probed on a chuck heated to 800 °C in N 2 or air. 1 The contact resistance ( R c W ) of the annealed contacts measured at room temperature was initially below 1 Ω mm. The R c W increased 3–4x when contacts were first probed at 800 °C in N 2 or air environments, an increase that can be explained in part by an elevated semiconductor sheet resistance, which increases the contact resistance by decreasing the transfer length of lateral contacts. After the contacts were held on the chuck at 800 °C for 1 h in N 2 , R c W increased modestly by 20%. Contacts held in air also remained ohmic, albeit with an increase in R c W of 120% due to the diffusion of oxygen. Upon cooling to room temperature, R c W of contacts stressed in N 2 for 1 h increased by 80% compared to unstressed contacts, and R c W of contacts aged in air for 1 h nearly doubled. However, no significant change in the semiconductor sheet resistance was observed compared to before heating. A closely related Ti/TaSi 2 /Pt contact was used in the source and drain of p -GaN–gated high electron mobility transistors 2 and amplifiers 3 with excellent performance at 800 °C, further highlighting the stability of the contact and barrier layer. X-ray diffraction showed that the deposited barrier layer was the hexagonal TaSi 2 phase. Cross-sectional field emission scanning electron microscopy with energy dispersive spectroscopy and x-ray photoelectron spectroscopy depth profiles gave us insight into the interlayer diffusion. While Ti remained at the contact interface even after stressing the contacts, a Pt cap interdiffused with the TaSi 2 barrier layer. In addition, some Ga and N diffused into the barrier layer. When the sample was held in air, incorporation of O was observed throughout the diffusion barrier, although incorporation of Ga and N was much more limited. Finally, we use this analysis, together with thermodynamic and kinetic data, to predict diffusion barriers that might outperform even TaSi 2 . This work at The Pennsylvania State University is supported by the Defense Advanced Research Project Agency (DARPA) under reward No. HR00112420331. C. W. Chiu et al., Mater Sci Semicond Process , 203 (2026) 110263. A. K. Visvkarma et al., IEEE Electron Device Letters , 46, 1509–1512 (2025). Y. Xiong et al., IEEE Electron Device Letters , 46, 1309–1312 (2025).

Semimetal contacts have recently emerged as promising due to the remarkably low contact resistance of Bi and Sb to n-channel field effect transistors (FETs) prepared from two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductors. However, hole injection in 2D semiconductors remains a bottleneck, hindering application of 2D devices in advanced logic nodes. In this study, we investigate the use of atomic layer deposition (ALD) to fabricate high work function semimetallic TiS x interlayers for efficient hole injection into WSe2, a 2D semiconductor of considerable interest due to its potential for next-generation scaled electronics. By employing ALD-grown semimetallic TiS x combined with capping the device with MoO x , we achieved a hole current of ∼64 µA µm-1 at V D = -1 V, a contact resistance of 10 ± 3 kΩ µm, and an I ON/I OFF ratio exceeding 106 at room temperature. Hole injection may be favored because of a high work function and low density of states at the Fermi level of TiS x , promoting a low Schottky barrier to the valence band of WSe2, and by the van der Waals nature of the contacts. Performance is further aided by channel doping by MoO x .

A gallium nitride bootstrapping amplifier integrated circuit is demonstrated for high-temperature applications. The amplifier leverages bootstrapping gain-boosting technology and incorporates five monolithically integrated depletion-mode gallium nitride high electron mobility transistors, enabling an operation temperature up to 800 degrees C in N-2 environment. Those transistors feature a threshold voltage of approximately -2 V. Under a gate-to-source voltage of 5 V, the on-state current density decreased from 167 mA/mm at 25 degrees C to 45 mA/mm at 800 degrees C. At 25 degrees C, the amplifier exhibits a DC gain of 26.3 dB with a unity gain frequency of 8.9 MHz. At 800 degrees C, the amplifier delivers a DC gain of 31 dB and a unity gain frequency of 1.4 MHz. In addition, no significant degradation was observed after holding the transistor and amplifier unbiased for an hour at 800 degrees C. This amplifier integrated circuit demonstrates the competitiveness of gallium nitride high electron mobility transistors as a promising technology for high-temperature electronics, up to 800 degrees C.

In this presentation, I will review recent work on contacts to group III nitride semiconductors, including two examples from our lab. Conductive metal nitrides are candidates for high-temperature, high-power Schottky diodes to n -type GaN. One of the metal nitrides in thermodynamic equilibrium with GaN that also has a high work function is Mo 2 N. Using bis (tertbutylimido) bis (dimethylamino) molybdenum, either a remote N 2 -H 2 plasma 1 or NH 3 was used as the co-reactant to deposit a conductive metallization. ALD offers an advantage over sputter deposition because deep levels can be created in GaN from the direct plasma during sputter deposition. ALD also has an edge over electron-beam evaporation because it is difficult to control the stoichiometry of nitride compounds during e-beam evaporation. Both types of ALD processes resulted in layers that contained some carbon, but the layers were good conductors, and there is significant solubility of MoC in Mo 2 N. Thermal ALD resulted in diodes with a Schottky barrier height of 0.69 eV and an ideality factor of 1.06 before annealing, while the remote-plasma process resulted in non-ideal diodes with high reverse currents. However, after annealing in N 2 at 600 °C, diodes prepared by both methods offered similar Schottky barrier heights (0.84 eV by thermal ALD and 0.87 eV by remote-plasma ALD). Inspired by prior work to “deconstruct” Ti/Al-based contacts to n-GaN, 2,3 we investigated the previously reported Zr/Al/Mo/Au 4–6 contact on Al x Ga 1-x N with x = 0.66–0.83 using the circular transfer length method and also examined the metallurgy of contacts to AlN. Zirconium is an interesting metal for contacts to AlN-rich compositions because Zr reacts with AlN at lower temperatures than many other metals, while Al, Mo, and Au are predicted to be unreactive with AlN based on thermodynamics. Preparing Zr/Al stacks without the Mo/Au cap, we found that Al-rich contacts (with a 1:4 ratio of Zr:Al) became ohmic on Al x Ga 1- x N with x = 0.67 after annealing at 800 °C, while Zr-rich contacts did not become ohmic even after annealing as high as 1150°C, highlighting the continuing importance of Al in the contacts to Al x Ga 1-x N with high x . Moreover, the thickness of Au in the capping layer also played a role in both the contact morphology and the required temperature to form ohmic contacts Al x Ga 1-x N with x = 0.66–0.67. An annealing temperature of 700 °C was optimal for the Au-rich contact, while a higher temperature of 950 °C was needed when the Au cap was thin, despite both contacts having similar specific contact resistance once they became ohmic (3–4 x 10 -4 Ohm-cm 2 ). Based on an examination of the contact morphology and relevant phase diagrams, we have formed a hypothesis that contacts that undergo partial melting can be prepared using lower annealing temperatures. References A. Molina et al., Appl. Phys. Lett. 119 102102 (2021) Luther, B. P. et al. Appl Phys Lett. 71, 3859–3861 (1997) Kwak, J. S. et al. Semicond. Sci. Technol. 15, 756–760 (2000) Hu, X. et al. IEEE Electron Device Lett. 39(10), 1568–1571 (2018) Yafune, N. et al. Electron Lett. 50(3), 211–212 (2014) Douglas, E. A. et al. physica status solidi (a) 214(8) 1600842 (2017) The authors gratefully acknowledge the support of ONR through N00014-22-1-2462 and N00014-23-1-2028. DISTRIBUTION STATEMENT A. Approved for public release distribution unlimited (DCN# 0543-1697-24 and DCN# 0543-1699-24).

We investigated Zr-based contacts to n-AlxGa1-xN with x = 0.66–0.83 using the circular transfer length method. Preparing Zr/Al stacks, we found that Al-rich contacts (with a 1:4 atomic ratio of Zr:Al) became ohmic on AlxGa1-xN with x = 0.67 after annealing at 750–800 °C, while Zr-rich contacts did not become ohmic even after annealing as high as 1150 °C, highlighting the importance of Al in the contacts to AlxGa1-xN with high x. The thickness of Au in the capping layer in Zr/Al/Mo/Au contacts also played a role in both the contact morphology and the required temperature to form ohmic contacts AlxGa1-xN with x = 0.66–0.67. An annealing temperature of 700 °C was optimal for the Au-rich contact, while a higher temperature of 950 °C was needed when the Au cap was thin, despite both contacts having nearly the same specific contact resistance once they became ohmic (3-4 × 10-4 Ω -cm2). Based on an examination of the contact morphology and relevant phase diagrams, we hypothesize that contacts that undergo partial melting can be prepared using much lower annealing temperatures. The best contact in this study to date was the Zr/Al contact with layer thicknesses of 39/111 nm on AlxGa1-xN with x = 0.67, which yielded a specific contact resistance of 1.5 × 10-4 Ω-cm2.

Electrical contacts to semiconductors are usually prepared by physical vapor deposition, but we explore thermal atomic layer deposition (ALD) to create molybdenum carbonitride-based Schottky diodes to gallium nitride. We also compare our findings to similar diodes that we previously prepared by plasma enhanced atomic layer deposition (PEALD). A stop-flow process was implemented to overcome a nucleation delay on gallium nitride during thermal ALD, which was not required for PEALD; however, the as-deposited diodes had better electrical behavior when prepared by thermal ALD. Current-voltage measurements reveal a higher as-deposited Schottky barrier height of 0.68±0.01eV and a lower ideality factor of 1.06±0.01 using thermal ALD. After annealing the diodes at 600 °C, the Schottky barrier height increased to 0.82±0.04eV, and the ideality factor decreased to 1.04±0.04, which are similar to annealed diodes prepared by PEALD. Although capacitance-voltage measurements indicate a higher barrier height (0.99 ± 0.1 eV) after annealing diodes prepared by thermal ALD, there was a minimal variation as a function of frequency. Together with the abrupt interface between the molybdenum carbonitride and gallium nitride observed by transmission electron microscopy, these measurements indicate a high-quality interface.

Atomic layer deposited TiS x forms semimetallic contacts to monolayer WSe 2 , enabling enhanced hole injection and improved p-FET performance.

A p-GaN gated high electron mobility transistor (HEMT) has been developed and electrically tested up to 800 degrees C. The device demonstrated a high on-state current of 80 mA/mm and simultaneously a high I-ON/I-OFF ratio of 770 at 800 degrees C. The transistor was also thermally stressed at 800 degrees C for 60 min. It demonstrated stable operation throughout the entire stress duration. The favorable on-current, on/off ratio, and stability show a promising path for high-temperature electronics based on GaN.

Considering the global and growing technological demand for platinum, increasing its utilization is key in the context of green hydrogen production by proton exchange membrane water electrolysis. An effective strategy to increase Platinum utilization in Pt/C hydrogen evolution electrocatalysts is to increase the Pt dispersion on the conductive carbon support and to reduce the Pt nanoparticle size down to Pt clusters or even Pt single sites. In that context utilization of 3D porous N-doped carbon supports is helpful to form and stabilize highly dispersed Pt species and achieve high mass activities. In here we present two approaches for the synthesis of such electrocatalysts with high Pt dispersion for hydrogen evolution: one based on a simple wet impregnation with subsequent thermal reduction, the other based on a vapor phase CVD deposition. We use N-doped mesoporous carbon nanospheres as supports, with high surface area and surface functionality to build Pt nanoparticles, clusters, and single sites. The Pt speciation, depending on the synthesis approach, was thereby investigated a. o. by XRD, XPS, ac-STEM, XAS and electrochemical CO stripping. In all cases, when high Pt dispersion was achieved in form of Pt clusters and single sites, ultra-high mass activity was demonstrated at the RDE level [1,2]. Literature: [1] Zeng, Z.; Küspert, S.; Balaghi, S. E.; Hussein, H. E. M.; Ortlieb, N.; Knäbbeler‐Buß, M.; Hügenell, P.; Pollitt, S.; Hug, N.; Melke, J.; Fischer, A. Small 2023, 2205885. [2] Küspert, S.; Campbell, I. E.; Zeng, Z.; Balaghi, S. E.; Ortlieb, N.; Thomann, R.; Knäbbeler‐Buß, M.; Allen, C. S.; Mohney, S. E.; Fischer, A. Small 2024, 2311260.

Two-dimensional (2D) molybdenum disulfide (MoS2) holds immense promise for next-generation electronic applications. However, the role of contact deposition at the metal/semiconductor interface remains a critical factor influencing device performance. This study investigates the impact of different metal deposition techniques, specifically electron-beam evaporation and sputtering, for depositing Cu, Pd, Bi, Sn, Pt, and In. Utilizing Raman spectroscopy with backside illumination, we observe changes at the buried metal/1L MoS2 interface after metal deposition. Sputter deposition causes more damage to monolayer MoS2 than electron-beam evaporation, as indicated by partial or complete disappearance of first-order E '(Gamma)(alpha) and A '(1)(Gamma)(alpha) Raman modes post-deposition. We correlated the degree of damage from sputtered atoms to the cohesive energies of the sputtered material. Through fabrication and testing of field-effect transistors, we demonstrate that electron-beam evaporated Sn/Au contacts exhibit superior performance including reduced contact resistance (similar to 12x), enhanced mobility (similar to 4.3x), and lower subthreshold slope (similar to 0.6x) compared to their sputtered counterparts. Our findings underscore the importance of contact fabrication methods for optimizing the performance of 2D MoS2 devices and the value of Raman spectroscopy with backside illumination for gaining insight into contact performance. (c) 2024 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/)

Intermetallic alloy phases and especially ordered intermetallic phases offer interesting chemical and physical properties. For example, many ordered intermetallics are attractive catalysts including Pt- and Pd-bearing phases. To better understand and exploit these materials, single crystals offer advantages. Here, we demonstrate the preparation of highly oriented or epitaxial thin films of the intermetallics PdCu, PtCu, PdIn, and PtAl2 on single-crystal MoS2. We find that cubic PdCu and PtCu films orient on MoS2 with the epitaxial relationship PdCu (111)||MoS2 (0001); PdCu[211]||MoS2 [1100] when cosputtered at room temperature. However, they are metastable disordered (or random) alloys. Upon annealing at 400 degrees C, we find evidence for ordering of PtCu. This ordered intermetallic is hexagonal and adopts the orientation PtCu (0001)||MoS2 (0001); PtCu[1100]||MoS2 [1100]. The ordered intermetallic PdIn forms at room temperature with the orientation PdIn (111)||MoS2 (0001); PdIn[110]||MoS2 [1100]; however, it is a textured film with a wide mosaic spread, even after annealing at 400 degrees C. The ordered PtAl2 intermetallic phase does not grow epitaxially at room temperature; however, upon annealing at 400 degrees C, we observe the PtAl2(100) face on MoS2(0001) rather than the initially expected PtAl2(111) face. The criteria we used previously to predict low-temperature epitaxy of elemental metals remain reliable (high adatom mobility, lack of reactivity with MoS2, and matching symmetry with the basal plane of MoS2). However, the presence of an order-disorder transition on the phase diagram, as found for PdCu and PtCu intermetallics, can sometimes promote the formation of a metastable disordered phase at room temperature despite epitaxy on MoS2.

Vapor-based deposition techniques are emerging approaches for the design of carbon-supported metal powder electrocatalysts with tailored catalyst entities, sizes, and dispersions. Herein, a pulsed CVD (Pt-pCVD) approach is employed to deposit different Pt entities on mesoporous N-doped carbon (MPNC) nanospheres to design high-performance hydrogen evolution reaction (HER) electrocatalysts. The influence of consecutive precursor pulse number (50-250) and deposition temperature (225-300 degrees C) are investigated. The Pt-pCVD process results in highly dispersed ultrasmall Pt clusters (approximate to 1 nm in size) and Pt single atoms, while under certain conditions few larger Pt nanoparticles are formed. The best MPNC-Pt-pCVD electrocatalyst prepared in this work (250 pulses, 250 degrees C) reveals a Pt HER mass activity of 22.2 +/- 1.2 A mg-1Pt at -50 mV versus the reversible hydrogen electrode (RHE), thereby outperforming a commercially available Pt/C electrocatalyst by 40% as a result of the increased Pt utilization. Remarkably, after optimization of the Pt electrode loading, an ultrahigh Pt mass activity of 56 +/- 2 A mg-1Pt at -50 mV versus RHE is found, which is among the highest Pt mass activities of Pt single atom and cluster-based electrocatalysts reported so far. Mesoporous N-doped carbon nanospheres are used for Pt deposition via a pulsed CVD approach. The process results predominantly in highly dispersed ultrasmall approximate to 1 nm sized Pt clusters along with Pt single atoms. The resulting electrocatalyst reveals an ultrahigh Pt hydrogen evolution reaction mass activity of 56 +/- 2 A mg-1Pt at -50 mV vs. RHE. image

The size of transistors has drastically reduced over the years. Interconnects have likewise also been scaled down. Today, conventional copper (Cu)-based interconnects face a significant impediment to further scaling since their electrical conductivity decreases at smaller dimensions, which also worsens the signal delay and energy consumption. As a result, alternative scalable materials such as semi-metals and 2D materials were being investigated as potential Cu replacements. In this paper, we experimentally showed that CoPt can provide better resistivity than Cu at thin dimensions and proposed hybrid poly-Si with a CoPt coating for local routing in standard cells for compactness. We evaluated the performance gain for DRAM/eDRAM, and area vs. performance trade-off for D-Flip-Flop (DFF) using hybrid poly-Si with a thin film of CoPt. We gained up to a 3-fold reduction in delay and a 15.6% reduction in cell area with the proposed hybrid interconnect. We also studied the system-level interconnect design using NbAs, a topological semi-metal with high electron mobility at the nanoscale, and demonstrated its advantages over Cu in terms of resistivity, propagation delay, and slew rate. Our simulations revealed that NbAs could reduce the propagation delay by up to 35.88%. We further evaluated the potential system-level performance gain for NbAs-based interconnects in cache memories and observed an instructions per cycle (IPC) improvement of up to 23.8%.

Two-dimensional (2D) semiconductors possess promise for the development of field-effect transistors (FETs) at the ultimate scaling limit due to their strong gate electrostatics. However, proper FET scaling requires reduction of both channel length (LCH) and contact length (LC), the latter of which has remained a challenge due to increased current crowding at the nanoscale. Here, we investigate Au contacts to monolayer MoS2 FETs with LCH down to 100 nm and LC down to 20 nm to evaluate the impact of contact scaling on FET performance. Au contacts are found to display a ∼2.5× reduction in the ON-current, from 519 to 206 μA/μm, when LC is scaled from 300 to 20 nm. It is our belief that this study is warranted to ensure an accurate representation of contact effects at and beyond the technology nodes currently occupied by silicon.

Nanostructured semiconductors are interesting because of their varied electronic and optical properties compared to the bulk. Using ordered porous materials as templates is an appealing approach to prepare nanostructured materials. However, the very small pore sizes (< 10 nm) of many mesoporous silicas make traditional deposition methods for germanium difficult, resulting in aggregated particles or voids in the deposited material. To overcome this challenge, high-pressure chemical vapor deposition (HPCVD) has been used to deposit germanium within the pore network of KIT-5 mesoporous silica. This technique allows for smooth, continuous deposition within small, tortuous pore networks. Both crystalline and amorphous materials can be produced, expanding the applicability of the resulting materials for various uses. The resulting nanocrystalline germanium has 5-nm features derived from the parent KIT-5 and is the smallest templated material prepared using HPCVD to date. This work represents the first time a three-dimensional mesoporous silica, with features ≤ 5 nm, has been uniformly filled with a semiconductor.