Experimental Detection and Control of Trions and Fermi-Edge Singularity in Single-Barrier GaAs/AlAs/GaAs Heterostructures Using Photocapacitance Spectroscopy

Abstract

In this paper, we show how photocapacitance spectra can probe two dimensional excitonic complexes and Fermi edge singularity as a function of applied bias around 100 K. In lower density regimes (<110 11 cm -2 ), the appearance of two distinct peaks in the spectra are identified as a signature of coexistence of both excitons and positively charged trions. We estimate the binding energy of these trions as ~2.0 meV. In the higher density regimes (>110 11 cm -2 ), we observe a sharp spectral transition from trions to asymmetric shaped Fermi edge singularity in the photocapacitance spectra around a particular reverse bias. However, these signatures are absent from the photoluminescence spectra measured under identical circumstances. Such dissimilarities clearly point out that different many body physics govern these two spectral measurements. We also argue why such quantum confined dipoles of spatially indirect trions can have thermodynamically finite probability to survive even around 100 K. Finally, our observations demonstrate that photocapacitance technique, which was seldom used to detect trions in the past, can also be useful to detect the traces of these spatially indirect excitonic complexes as well as Fermi edge singularity even at 100 K. This is mainly due to enhanced sensitivity of such dielectric measurements to dipolar changes within such heterojunction. 3 I.

Influence of Indium Composition on InAlAs QCLs

“…These energy states can trigger Fermi-edge singularity (FES) phenomena, leading to abnormal luminescence and anomalous carrier transport behaviors [15,16]. FES can signi cantly impact device performance parameters, such as reduced carrier mobility [17], enhanced kink-effect in resonant tunneling [18], cotunneling during single-electron transport [19], increased electron-phonon coupling [20], and elevated electron-electron scattering in photodiodes [21][22][23].…”

Correlation between Optical Localization-State and Electrical Deep-Level State in In0.52Al0.48As/In0.53Ga0.47As Quantum Well Structure

“…According to previous literature, those energy states may cause the Fermi-edge singularity (FES) phenomena [16][17][18][19][20][21], leading to the abnormal luminescence [21][22][23] and the anomalous carrier transport behaviors [24]. Furthermore, such an FES is known to significantly affect the device performances (e.g., decreased carrier mobility [25,26], increased kink-effect in resonant tunneling [27], cotunneling during the single-electron transport [28], increased electron-phonon coupling [29], increased electron-electron scattering in the photodiode [30], etc.). Based upon the above, one can conjecture that the FES-related states should be simultaneously represented with both the electronic band structures and the energy band diagram, respectively.…”