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Codoping of gallium nitride for improved acceptor ionization has long been theorized; however, reduction to practice proves difficult via growth. Herein, implementation of codoping via ion implantation and symmetric multicycle rapid thermal annealing utilizing magnesium codoped with silicon or oxygen is demonstrated. Results show enhanced photoluminescence with both donor species but with an order of magnitude greater increase with concurrent p‐type hall for codoping with oxygen. Furthermore, the addition of nitrogen to balance stoichiometry suppresses defect photoluminescence signals. The incorporation of the donor and nitrogen demonstrates defect reduction beyond magnesium, only implants despite the additional implant dose and resultant damage with coimplantation. The enhanced hole concentrations evident with oxygen incorporation reveal important considerations for device design given unintentional doping during growth and future incorporation of ion implantation capabilities. [ABSTRACT FROM AUTHOR]

Herein, the electrical and thermal performance of lateral AlGaN/GaN high electron mobility transistors (HEMTs) and metal‐insulator‐semiconductor field effect transistors (MISFETs) fabricated with 11 μm thick GaN buffer layers on 200 mm diameter Qromis Substrate Technology (QST) substrates are investigated. The QST substrate has a polycrystalline core engineered to be coefficient of thermal expansion (CTE)‐matched to GaN to minimize wafer bow and residual stress in the GaN film as a result of epitaxial growth. Raman spectroscopy is used to determine the biaxial residual stress in the GaN buffer of the as‐fabricated devices. Electrical characterization is demonstrated on the HEMTs including DC and pulsed output characteristics, DC transfer characteristics, Hall mobility, carrier concentration, sheet resistance, median transition frequency, and maximum stable gain. Finally, the thermal performance of the AlGaN/GaN MISFET is assessed via thermoreflectance thermal imaging at DC power densities up to 19 W mm−1. The thermal resistance of the MISFET, calculated using the peak temperature rises on the gate electrode for DC power densities <10 W mm−1, is measured to be 15.4 mm K W−1, which is comparable with state‐of‐the‐art GaN‐on‐Si lateral transistors. [ABSTRACT FROM AUTHOR]

AlGaN/GaN high electron mobility transistors on QST engineered substrates are grown with different GaN/AlGaN buffer layer thickness. The as‐grown heterostructures are evaluated for their structural quality via atomic force microscopy, high‐resolution X‐ray diffraction, Raman spectroscopy, and steady‐state thermoreflectance. Transistor devices are fabricated and evaluated via DC and pulsed electrical techniques, as well as thermoreflectance imaging. It is reported that buffer layer thickness of at least 10 μm can result in lateral high electron mobility transistors (HEMTs) with simultaneously high GaN quality, low stress, good DC electrical performance, low current collapse, and low thermal resistance. [ABSTRACT FROM AUTHOR]

Ion implantation of magnesium for p‐type GaN presents many opportunities; however, activation has proven difficult due to the decomposition of GaN at relevant annealing temperatures. Herein, testing the efficacy of multiple in situ and ex situ caps based on aluminum nitride and silicon nitride for GaN protection during annealing is presented. Photoluminescence shows better activation for in situ metal organic chemical vapor deposition (MOCVD)‐grown aluminum nitride caps compared with ex situ sputtered aluminum nitride and the best performance by ex situ plasma‐enhanced chemical vapor deposition (PECVD) silicon nitride. Furthermore, only samples annealed at the highest temperatures tested show preferential growth of UV luminescence to yellow‐green luminescence reinforcing the need for better capping solutions and higher temperature annealing. [ABSTRACT FROM AUTHOR]

Top-side integration of nanocrystalline diamond films in the fabrication sequence of AlGaN/GaN high electron mobility transistors is demonstrated. Reliable oxygen plasma etching of the diamond capping layer, required for a diamond-before-gate process, was implemented by using a sacrificial SiN 'dummy' gate. Hall characterization showed minimal (∼6%) reduction in sheet carrier density and commensurate increase in sheet resistance, while maintaining mobility and on-state drain current density. Off-state drain current and threshold voltage were increased, likely by fluorination of the AlGaN surface after removal of the sacrificial gate, even though a 20 nm thick Al2O3 layer was used as a SF6-plasma etch stop. Pulsed IDS and on-resistance were improved, indicating that a 10 nm SiN/500 nm NCD could offer improved AlGaN surface passivation compared to a more conventional 100 nm thick PECVD SiN film. [ABSTRACT FROM AUTHOR]

An Mg-implanted p-i-n diode was fabricated and characterized. Mg activation was achieved using the multicycle rapid thermal annealing technique with rapid heating pulses up to 1340 °C. The surface of the implanted GaN after annealing was smooth (0.94 nm RMS roughness) with growth steps evident as characterized by atomic force microscopy. The full width at half-maximum of the implanted GaN E2 Raman mode approaches that of the as-grown GaN after the annealing process, indicating that the annealing process is able to reverse most of the implantation damage. The Mg-implanted p-i-n diode exhibits rectification and a low leakage current of 0.11 μA cm−2 at a bias of −10 V. Under forward bias, light emission was observed from the p-i-n diode. The implantation and activation of Mg in a GaN-based device, demonstrated for the first time in this research, is a key enabling step for future optoelectronic and power electronic devices. Current-voltage characteristics of the Mg-implanted p-i-n diode with an inset of the device schematic. [ABSTRACT FROM AUTHOR]

Activation of ion‐implanted p‐type dopants in gallium nitride has demonstrated great progress utilizing high pressures to enable novel and traditional device architectures; however, such conditions consistently exhibit anomalously enhanced diffusion up to several microns in very short periods of time for device relevant concentrations. Here, this diffusion is shown to be modulated by unintentional hydrogen content within the anneal ambient and thus controllable by inclusion of a high‐temperature hydrogen getter. Furthermore, diffusion is also shown to be greatly suppressed using co‐implanted oxygen at low concentrations while simultaneously maintaining characteristics of p‐type material in photoluminescence. Subsequently, after annealing at 1300 °C for 30 min in 3.8 kbar of nitrogen pressure, the magnesium concentration in the diffusion tail is suppressed by 28% at 1–1.5 μm in depth using a hydrogen getter alone, which reduces hydrogen uptake by 45% and fully suppressed at >1 μm in depth using co‐implantation alone and further reduced with concurrent use of a hydrogen getter. Co‐implantation alone reduces the in‐diffused magnesium dose by 60% compared to reference samples. [ABSTRACT FROM AUTHOR]