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Improvement of electrical characteristics in regrown AlGaN/GaN MOSFETs by suppression of the residual interface charge
摘要： In this paper, the influence of a regrown interface on the electrical properties of AlGaN/GaN heterostructure was investigated for recessed-gate MOSFETs fabricated by selective area regrowth. The electron mobility of the two-dimensional electron gas (2DEG) on regrown AlGaN/GaN structures was degraded when the 2DEG was near the regrown interface. The regrown interface had high carrier concentrations and Si impurities that caused degradation of the electron mobility of the 2DEG. Unintentional carrier generation at the regrown interface was eliminated by ultraviolet (UV) treatment before regrowth. A regrown AlGaN/GaN MOSFET device was then fabricated using the UV treatment. The device exhibited good performance such as normally-off operation without hysteresis or leaks. Improvement of the electrical characteristics of AlGaN/GaN MOSFETs was thus achieved by suppression of regrown interface charge.
关键词： B2. Semiconducting gallium compounds,B3 High electron mobility transistors,A1. Interfaces,A3. Metalorganic vapor phase epitaxy,B1. Nitride
更新于2025-09-23 15:22:29
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Structural disorder and in-gap states of Mg-implanted GaN films evaluated by photothermal deflection spectroscopy
摘要： Both structure of the valence band maximum (VBM) and deep-level defects for box-pro?le Mg-ion implanted (4 × 10^19 cm^-3) GaN samples are characterized by photothermal de?ection spectroscopy (PDS). Compared with the results evaluated by positron annihilation spectroscopy, the variations caused by the thermal annealing is discussed with respect to Urbach energy, defect levels in the band gap, and photoluminescence. Forming Urbach tail gradually at the VBM at the 1000 °C annealing, vacancy-type defects clusters without drastic decrease of deep-level defects. Green and yellow luminescence emits slightly as the PDS signal at the deep-level is decreased by the annealing at 1100 °C due to the decrease of non-radiative recombination centers. The Urbach energy is improved by the further annealing so that the luminescence becomes intense due to the energy transfer through the phonon from Urbach region. The shift of Fermi level towards the valence band at the 1300 °C annealing, the sign of p-conduction, is con?rmed from the valence band spectra. Compared to the Mg-doped GaN with p-conduction, it is considered that the improvement of Urbach energy is crucial for p-type activation.
关键词： B1. Gallium compounds,B1. Nitrides,A1. Defects
更新于2025-09-19 17:15:36
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Room-temperature photoluminescence of AP-MOVPE grown single GaSb/GaAs quantum dot layer
摘要： The effect of GaAs host matrix on excitonic behaviour in AP-MOVPE grown GaSb/GaAs quantum dots (QDs) was investigated. Room temperature (RT) photoluminescence (PL) emission was achieved from single layers of quantum dots by controlling the GaAs host matrix growth temperature. Samples were prepared using a GaSb dot growth temperature of 530 °C, followed by growth of a thin GaAs ‘cold’ cap, before depositing the final part of the GaAs capping layer at either 550 °C, 600 °C or 650 °C. PL measurements at 10 K revealed QD emission peaks for all the samples at around 1.1 eV. However, variable temperature PL revealed different thermal quenching rates of the emission, with the rates of quenching reduced with increasing GaAs growth temperature. This was ascribed to reduced defect densities in GaAs grown at higher temperature, which resulted in QD emission even at RT. The hole localisation energy determined for these samples at RT was approximately 470 meV.
关键词： Defects,Antimonides,Metalorganic vapor phase epitaxy,Nanostructures,Gallium compounds
更新于2025-09-12 10:27:22