Systematic study of shockley-read-hall and radiative recombination in GaN on Al₂O₃, freestanding GaN, and GaN on Si

Abstract

Here we study and correlate structural, electrical, and optical properties of three GaN samples: GaN grown by metalorganic chemical vapor deposition on sapphire (GaN/Al2O3), freestanding GaN crystals grown by the high nitrogen pressure solution method (HNPS GaN), and GaN grown by hydride vapor phase epitaxy on silicon (GaN/Si). Defect and impurity densities and carrier concentrations are quantified by x-ray diffraction, secondary mass ion spectroscopy, and Hall effect studies, respectively. Power-dependent photoluminescence measurements reveal GaN near-band-edge emissions from all samples having mixtures of free exciton and band-to-band transitions. Only the defect luminescence in the GaN/Si sample remains unsaturated, in contrast to those from the HNPS GaN and GaN/Al2O3 samples. Carrier lifetimes, extracted from time-resolved photoluminescence measurements, and internal quantum efficiencies, extracted from temperature-dependent photoluminescence measurements, are used to extract radiative and nonradiative lifetimes. Shockley–Read–Hall (A) and radiative recombination coefficients (B) are then calculated accordingly. Overall, the A coefficient is observed to be highly sensitive to the point defect density rather than dislocation density, as evidenced by three orders of magnitude reduction in threading dislocation density reducing the A coefficient by one order of magnitude only. The B coefficient, while comparable in the higher quality and lowly doped GaN/Al2O3 and HNPS GaN samples, was severely degraded in the GaN/Si sample due to high threading dislocation density and doping concentration.

Fabrication of gallium nitride and nitrogen doped single layer graphene hybrid heterostructures for high performance photodetectors

“…As mentioned earlier, nitrogen doping regulates the property of graphene by maintaining good conductivity and carrier mobility 31 . The obtained mobility value is higher than that of the standard mobility value of GaN and also falls within the mobility range for nitrogen doped SLG as reported in literature 46,72 . The hall measurement data corroborate with I-V results.…”

Estimation of Shockley–Read–Hall Lifetime in Homoepitaxial n‐GaN on Low‐Dislocation‐Density GaN Substrates Prepared by Hydride Vapor Phase Epitaxy and Maskless 3D

“…Meyer et al [41] and Ščajev et al [42] studied carrier lifetimes using temperature-dependent time-resolved photoluminescence. Meyer et al studied SRH recombination in MOVPE grown GaN layers on a Si substrate [N dis ¼ (5.6 AE 0.1)Â10 10 cm À2 ], a sapphire substrate (N dis ¼ 2.9 Â 10 8 cm À2 ), and a freestanding GaN substrate grown by the high nitrogen pressure solution method [N dis ¼ (2.8 AE 0.1)Â10 7 cm À2 ].…”

“…Meyer et al studied SRH recombination in MOVPE grown GaN layers on a Si substrate [N dis ¼ (5.6 AE 0.1)Â10 10 cm À2 ], a sapphire substrate (N dis ¼ 2.9 Â 10 8 cm À2 ), and a freestanding GaN substrate grown by the high nitrogen pressure solution method [N dis ¼ (2.8 AE 0.1)Â10 7 cm À2 ]. [41] Ščajev et al, in contrast, studied the ambipolar lifetime τ a in 1À3 Â 10 16 cm À3 doped HVPE n-GaN layers (N dis ¼ 0.14À1.3 Â 10 8 cm À2 ) under high excitation conditions (pÀN d ¼ 0.1À5 Â 10 19 cm À3 ). [42] As τ a is expressed from charge neutrality as…”

Design and Simulation of Near-Terahertz GaN Photoconductive Switches--Operation in the Negative Differential Mobility Regime and Pulse Compression

“…The value of τ 0 depends strongly on the threading dislocation density as a result of the heteroepitaxial growth of GaN on non-native substrates, as well as point defect (i.e., vacancy and impurity) concentration, which is subject to material growth chemistry and conditions. The non-radiative carrier lifetime in GaN on Al 2 O 3 (Si) grown via metalorganic chemical vapor deposition (MOCVD) is reported to be ≈ 400 ps (250 ps) at room temperature in [23]. The power-dependent photoluminescence measurements showed a strong yellow luminescence (YL) at 2.25 eV in both GaN on Al 2 O 3 and GaN on Si samples.…”

“…The power-dependent photoluminescence measurements showed a strong yellow luminescence (YL) at 2.25 eV in both GaN on Al 2 O 3 and GaN on Si samples. The YL band was attributed to V Ga and C N -related defects [23]. In [24], it was shown that for GaN epilayers deposited on high-quality AlN buffer grown on sapphire using migrationenhanced MOCVD, τ 0 ≈ 2 ns at room temperature.…”