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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

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

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Bhunia, Amit [1, 2] ; Singh, Mohit Kumar [1, 2] ; Gobato, Y. Galvao [3, 4] ; Henini, Mohamed [5, 6] ; Datta, Shouvik [1, 2]
Total Authors: 5
[1] Indian Inst Sci Educ & Res, Dept Phys, Pune 411008, Maharashtra - India
[2] Indian Inst Sci Educ & Res, Ctr Energy Sci, Pune 411008, Maharashtra - India
[3] Univ Fed Sao Carlos, Dept Fis, BR-13560905 Sao Carlos, SP - Brazil
[4] Radboud Univ Nijmegen, EMFL, HFML, NL-6525 ED Nijmegen - Netherlands
[5] Univ Nottingham, Sch Phys & Astron, Nottingham NG7 2RD - England
[6] Univ South Africa UNISA, Coll Grad Studies, UNESCO UNISA Africa Chair Nanosci & Nanotechnol L, POB 392, Pretoria - South Africa
Total Affiliations: 6
Document type: Journal article
Source: PHYSICAL REVIEW APPLIED; v. 10, n. 4 OCT 17 2018.
Web of Science Citations: 0

We show how photocapacitance spectra can probe and manipulate two dimensional excitonic complexes and Fermi-edge singularities as a function of applied bias even at a temperature of 100 K. For lower density regimes (< 1x10(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 find the binding energy of these trions to be approximately 2.0 meV, which matches well with known estimates. For higher density regimes (> 1x10(11) cm(-2)), we observe a sharp spectral transition from trions to asymmetrically shaped Fermi-edge singularities in photocapacitance spectra above a particular reverse bias. However, these signatures of indirect excitonic states are absent from photoluminescence spectra. 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 spectroscopy, which was rarely 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 singularities. This is mainly due to the enhanced sensitivity of these capacitive measurements to `` dipolar{''} changes of excitonic complexes in these heterojunctions. Thus, our studies clearly open up future possibilities for electro-optical modulation and detection of trions and Fermi-edge singularities in several other heterostructures for next-generation optoelectronic applications. (AU)

FAPESP's process: 18/01808-5 - Optical and Transport Properties in High Magnetic Fields of Semiconductor Heterostructures and Devices based on Two Dimensional Materials
Grantee:Yara Galvão Gobato
Support type: Scholarships abroad - Research
FAPESP's process: 16/10668-7 - Optical and Transport Properties of two-dimensional semicondutors based on transition metal dichalcogenides
Grantee:Yara Galvão Gobato
Support type: Regular Research Grants