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Surface photovoltage spectroscopy of quantum well and quantum dot systems

Piotr Sitarek 1Jan Misiewicz 1Ying-Sheng Huang 2

1. Wroclaw University of Technology, Institute of Physics, Wybrzeże Wyspiańskiego 27, Wrocław 50-370, Poland
2. National Taiwan University of Science and Technology, Department of Electronic Engineering, Taipei 0106, Taiwan

Abstract

Surface photovoltage spectroscopy (SPS) has been used for many years to study the properties of electronic states near the surface in bulk semiconductors. With the advent of crystal growth techniques, allowing the production of high quality semiconductor heterostructures, SPS spectroscopy found additional applications. It was used to study electronic states in heterostructures, quantum wells (QW’s), quantum dots (QD’s) and also electronic device structures.

We present room temperature SPS results obtained on MBE grown semiconductor structures with QW’s and QD’s. Obtained results were compared with other spectroscopic methods like photoluminescence (PL) and photoreflectance (PR).

The SPS measurements were performed at contactless mode at normal incidence using a probe light chopped at 160 Hz. The absence of electric contacts makes a contactless mode more convenient to perform and non-destructive comparing to standard surface photovoltage measurements.

We have investigated GaAsSb/GaAs and GaAs/InGaAs/AlGaAs QW structures. In both cases SPS measurements gave us additional information about QW’s electronic structure comparing to PL and PR. In case of GaAsSb/GaAs QW’s the SPS spectra show additional features corresponding to optical transitions between light hole state in valence band and electronic state (1lh-1e) and conduction band edge (1lh-cb) in conduction band. In GaAs/InGaAs/AlGaAs QW case, SPS spectra give us some information about band offset between semiconductors forming QW.

Except of QW structures we have investigated InGaAs/GaAs single layer QD structures and InAs/GaAs vertically stacked QD structures. Obtained spectra usually show additional features, connected with higher energy QD optical transitions, comparing to PL and PR.

Surface photovoltage spectroscopy with photoluminescence and photoreflectance are turning out to be supplementary techniques for investigating semiconductor heterostructures (QW’s, QD’s) and device (VCSEL, laser) structures.
 

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Related papers

Presentation: Oral at E-MRS Fall Meeting 2007, Symposium H, by Piotr Sitarek
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-11 10:02
Revised:   2009-06-07 00:44