Lifetime Assessment of In_xGa_1−xAs n‐Type Hetero‐Epitaxial Layers

Abstract

Herein, the carrier lifetime in ≈5 × 1016 cm−3 n‐doped In x Ga1−x As layers is studied by diode current–voltage analysis and by time‐resolved photoluminescence. Two sets of hetero‐epitaxial layers are grown on semi‐insulating InP or GaAs substrates. The first set corresponds with a constant In content p + n stack, while the second set has a fixed x = 0.53 for the n‐layer, while containing various extended defect densities by using a strain relaxed buffer with different x. This results in threading dislocation densities (TDDs) between ≈105 cm−2 and a few 109 cm−2. It is shown that the overall trend of the recombination lifetime versus TDD can be described by a first‐order model considering a finite recombination lifetime value inside a dislocation core of 1 nm. For the generation lifetime, a strong electric‐field enhancement factor is found. Also, the residual strain in the n‐layer has an impact. Overall, the safe limit for TDD depends on the type of application and on the operation conditions (reverse diode bias).

Sub‐second Lifetime of Photocarriers in Hybrid Lead Halide Perovskite

“…It is noted that τ 1 is below 100 ns and τ 2 is close to 1 µs for MAPbI 3 single crystal pumped by the light with the intensity of 2.5-25 mW cm −2 , [5,6] and both τ 1 and τ 2 slightly decrease with the intensity increasing (Figure S3, Supporting Information). [18] Besides, an mm-size crystal was grinded to prepare µm-scale crystal grains and their τ 1 and τ 2 only slightly change, because the big crystal and the small crystal grains have the similar surface layers for PL spectra emitting. Furthermore, the transient PL spectra of Au/MAPbI 3 sample were characterized and the τ 1 and τ 2 abruptly shorten to 13.2 and 134.9 ns mainly due to the interfacial defects trap photocarriers and the decrease of the diffusion length.…”