This Letter studies the reverse leakage and breakdown mechanisms of vertical GaN-on-Si Schottky barrier diodes (SBDs) with and without argon-implanted termination (ArIT). The electrical leakage characteristics in the vertical GaN-on-Si SBD without edge termination sequentially go through the thermionic field emission, variable range hopping (VRH), and trap-assisted tunneling conduction mechanisms as the reverse bias increases gradually. Its leakage and breakdown mechanisms are limited by the edge electric field crowding effect. While for the vertical GaN-on-Si SBD with ArIT (ArIT-SBD), the electrons conduction at a low reverse bias, following the space-charge-limited conduction (SCLC) model, is limited by the damage-induced traps in the implanted GaN. As the reverse bias increases up to the occurrence of breakdown, the VRH and SCLC dominate the leakage mechanism of the ArIT-SBD, which stem from intrinsic traps in GaN grown on Si. A rapidly growing leakage under a low reverse bias and enhanced breakdown voltage performance in the ArIT-SBD is attributed to the charging of the damage-induced traps in implanted GaN. This Letter not only gives in-depth insights of vertical GaN-on-Si SBDs but also provides a useful design guidance of implanted termination for high-voltage power devices.

This work reports 1200-V quasi-vertical GaN-on-Si p-n diodes with a 6.6-μm-thick high-quality GaN drift layer showing excellent static and dynamic performance. The as-fabricated GaN-on-Si p-n diode gives a high current on/off ratio of ~10 ¹⁰ , a low ideality factor of 1.2, a low specific on-resistance (R _on,sp ) of 1.3 mΩ∙cm ² , and a high breakdown voltage (BV) of 1210 V. The p-n diode can properly operate at a high temperature of 175 °C, and the device performance can be effectively recovered after the power cycling test. A reduced dynamic on-resistance (R _on ) dependence on the off-state voltage (V _OFF ) and on-state conduction time (T _ON ) is observed in this p-n diode and attributed to the filling dynamics of electron traps. A normalized dynamic R _on of 0.7 is realized after switching from a V _OFF stress at 1000 V. As the first 1200-V GaN-on-Si vertical power device, this cost-effective p-n diode with high performance holds a great promise for high-voltage power applications.

Semiconductor nano-membranes provide a new way to develop optical devices with better performance. Herein, we report a fabrication method of GaN-based LED membranes with a complete device structure including contact metals from Si substrate by using electrochemical etching of highly conductive AlN/Si interface, which is often naturally formed in GaN-on-Si materials. Photoluminescence and Raman scattering spectra show that the internal stress after the lift-off was effectively lightened with 1.45 GPa. Electrical measurement results show that both the leakage current and series resistance were largely decreased, and strong and uniform electroluminescence further proved the well-preserved whole structure.

Time-resolved photoluminescence and capacitance-voltage measurement were performed on p-type GaN and InGaN films to study the minority carrier recombination mechanism. The minority carrier lifetime (τ _PL) for p-GaN with a Mg concentration of 1.7 × 10¹⁹ cm⁻³ was 46 ps. The non-radiative recombination due to gallium vacancies (V _Ga)-related defects is confirmed to dominate the minority carrier transport process. To suppress the formation of V _Ga defects, the indium atoms were added into p-GaN. As a consequence, the V _Ga-related non-radiative recombination centers were reduced from 8 × 10¹⁵ to 5 × 10¹⁴ cm⁻³ and a record long τ _PL of 793 ps was obtained for p-In_0.035Ga_0.95N film.

The characteristics of an AlGaN/GaN high-electron-mobility transistor buffer structure are studied and optimized by employing an AlN/GaN superlattice (SL) structure. Through vertical leakage analysis and back-gate measurement, combined with Silvaco-TCAD simulation, the influence of buffer trapson the carrier transport behaviors and electrical performance for SL buffer structures under a high electric field is analyzed. The AlN/GaN SL buffer structures are further optimized with various AlN/GaN thickness ratios and their total thickness through both simulation and experimental studies. As a result, a high breakdown voltage of up to 1.3 kV with a maximum breakdown electric field of 2.8 MV cm⁻¹ has been achieved. Moreover, the buffer trapping effect is dramatically suppressed, leading to a minimum drop of channel current for the optimized sample, in which donor traps are found to play a positive role in the device dynamic characteristics.

The influence of energy band structure on the electrical characteristics of GaN-based double-heterojunction bipolar transistors (DHBTs) has been studied through both simulation and fabrication. According to the simulation result, a novel DHBT structure with a composition graded base was grown and fabricated. A long minority carrier lifetime of 4.08 ns has been achieved for the composition graded p-InGaN base with a greatly improved material quality. The indium composition grading of the p-InGaN base layer combined with Si doping profile tuning for the collector layer was proposed to eliminate the energy barrier usually formed at the conventional GaN/InGaN/GaN base–collector (B–C) junction interface due to the band discontinuity and polarization effect. As a result, the as-fabricated DHBT presents a high intercept voltage of 225 V extracted from the $\textit{I}_{\textit{C}}$ – $\textit{V}_{\text{CE}}$ curves and a high current gain of 49.