Temperature-dependent contactless electroreflectance and photoluminescence study of GaAlAs/InGaAs/GaAs pseudomorphic high electron mobility transistor structures

Abstract

Temperature-dependent contactless electroreflectance (CER) and photoluminescence (PL) measurements in the range of 30 K<T<300 K on two GaAlAs/InGaAs/GaAs pseudomorphic high electron mobility transistor structures with different well widths fabricated by molecular-beam epitaxy on (100) GaAs substrates are presented. For the CER measurement, the 11H transition is completely screened out by the two-dimensional electron gas and the prominent feature related to the Fermi energy edge singularity transition showed a Stokes shift to higher energy with respect to the 21H transition of the PL measurements at low temperature. From the Stokes shifts, the Fermi energy level of the system is evaluated, and hence, the density of the two-dimensional electron gas. The temperature-dependent PL measurements revealed two features, identified to be the 11H and 21H transitions. The relative intensities of the 11H and 21H transitions were analyzed taking into account the effect of the subband filling and the wave-function overlap factors. A good agreement is found between experimental data and theoretical calculation results.

Differential surface photovoltage spectroscopy of δ‐doped GaAs/AlAs multiple quantum wells below and close to Mott transition

“…2, dashed curve). In general, our observations are in agreement with many experimental investigations showing that the features associated with optical transitions involving filled subbands are rather weak or even unobservable both in absorption [6,18] and various differential spectra, including the DSPV ones [24][25][26]. Enhanced absorption peaks near the Fermi energy known as the Fermi edge singularities [15] usually manifest themselves only at very low temperatures, therefore, in our case are hardly probable.…”

“…1). Moreover, it should be noted that similar broad features were also found in the photomodulation [21,24], electromodulation [21,25] and the DSPV spectra [26] of welldoped GaAs/AlGaAs QWs [21] and modulation-doped AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor structures [24][25][26]. They were accounted for on the basis of exciton screening by the two-dimensional electron gas combined with phase-space filling effects.…”

InGaAs/GaAsP Superlattice Resonant Cavity-Enhanced Photodetector Fabricated on a Nominal Si(001) Substrate for Near- and Short-Wavelength Infrared Applications

“…The redshift of the emission peaks with respect to their absorption counterparts in the spectrometric data (Figure 6), meanwhile, can likely be attributed to a disorder-induced Stokes shift. 41,42 A cursory comparison can be made with a simple Schrodinger 1-band model (Figure 7b), especially the fundamental transition, calculated at 1.30 eV (e1−hh1) with an interband matrix element of ∼0.96 and 1.37 eV (e2−hh2) with an interband matrix element of 0.86. 35 The latter energy corresponds to a wavelength of ∼905 nm and is likely partly responsible for the energetic tail present at lower wavelengths, which itself is a convolution of such factors as other energetic transitions with low interband matrix elements as well as local inhomogeneities in the crystal structure.…”

Optoelectric Properties of GaInP p-i-n Solar Cells with Different i-Layer Thicknesses

“…In addition, the different thicknesses of an i-layer would be studied in detail because the thicker i-layer may induce more defects and lower the built-in electric field. Modulation spectroscopy is a powerful tool for studying optical fine structures in semiconductor devices and materials [4][5][6][7][8][9]. In order to evaluate the i-layer quality, a systematic optical characterization of thickness and built-in electric field must be clarified for giving us information in order to optimize the power conversion efficiency.…”