Cryogenic Pressure and Lifetime Studies of a Defect Related Emission in Heavily Silicon Doped GaAs

Abstract

We have used cryogenic high pressure measurements and lifetime studies to investigate a defect related emission at 1.269eV in silicon doped GaAs. The pressure measurements prove that the 1.269eV photon energy is relative to the conduction band. This implies a deep defect level N 0.30 eV above the valence band and an electron capture process from near the conduction band into the defect. The defect level moves up in the bandgap at a rate of (23 f 3) meV/GPa. Between 20 K and room temperature the defect emission lifetime remains constant at (9.63 f 0.25) ns, while the intensity decreases over this same range. We explain this surprising result using an intradefect emission process. These results are consistent with a vacancy related defect level, possibly stemming from a gallium vacancy-silicon at gallium (second-nearest-neighbor) defect complex.

Solution Phase Synthesis of Indium Gallium Phosphide Alloy Nanowires

“…The PL decay kinetics are fit to a biexponential decay function with short component lifetimes of 0.034 ± 0.0006, 0.026 ± 0.0003, and 0.16 ± 0.004 ns and long component lifetimes of 0.78 ± 0.008, 0.96 ± 0.01, and 1.51 ± 0.02 ns for NWs with compositions x = 0.21, 0.41, and 0.84, respectively. A biexponential fit with a slow component of 0.5–2.0 ns is typical for radiative band to band recombination in a direct band gap semiconductor, and the measured lifetimes are consistent with those previously reported for direct band gap In x Ga 1– x P of 1–3 ns. , This provides additional evidence that the luminescence observed is from a band to band radiative recombination as opposed to processes such as defect emission or indirect band gap emission, which have radiative lifetimes on the order of tens of nanoseconds to microseconds. , The control of PL emission from the visible to NIR energy range is expected to have applications toward tunable In x Ga 1– x P-based LEDs and NW lasers.…”

“…63,64 This provides additional evidence that the luminescence observed is from a band to band radiative recombination as opposed to processes such as defect emission or indirect band gap emission, which have radiative lifetimes on the order of tens of nanoseconds to microseconds. 41,65 The control of PL emission from the visible to NIR energy range is expected to have applications toward tunable In x Ga 1Àx P-based LEDs and NW lasers. The band gap of the NWs was next recorded with UVÀvisÀNIR absorption measurements using an integrating sphere setup.…”

Hydrostatic pressure coefficients of the valence band maximum in Ge, InSb, InAs, and GaAs

“…According to the study of Frogly and Dunstan [19] the coefficient of pressure ∂ε g /∂P = 116 meV/GPa. Experimentally, pressure coefficients ∂(ε C -ε i )/∂P = 100 to 106 meV/GPa [5] and ∂(ε i -ε V )/∂P = (23 ± 3) meV/GPa [9], where ε i -ε C = 200 meV and ε i -ε V = 300 meV at P = 0 GPa. From here ∂ε V /∂P ≈ -16 meV/GPa.…”