Electroreflectance studies of Stark shifts and polarization-induced electric fields in InGaN/GaN single quantum wells
- 1 May 2004
- journal article
- research article
- Published by AIP Publishing in Journal of Applied Physics
- Vol. 95 (9), 4905-4913
- https://doi.org/10.1063/1.1690100
Abstract
To observe the effects of polarization fields and screening, we have performed contacted electroreflectance (CER) measurements on single quantum well light emitting diodes for different reverse bias voltages. Room-temperature CER spectra exhibited three features which are at lower energy than the GaN band gap and are associated with the quantum well. The position of the lowest-energy experimental peak, attributed to the ground-state quantum well transition, exhibited a limited Stark shift except at large reverse bias when a redshift in the peak energy was observed. Realistic band models of the quantum well samples were constructed using self-consistent Schrödinger–Poisson solutions, taking polarization and screening effects in the quantum well fully into account. The model predicts an initial blueshift in transition energy as reverse bias voltage is increased, due to the cancellation of the polarization electric field by the depletion region field and the associated shift due to the quantum-confined Stark effect. A redshift is predicted to occur as the applied field is further increased past the flatband voltage. While the data and the model are in reasonable agreement for voltages past the flatband voltage, they disagree for smaller values of reverse bias, when charge is stored in the quantum well, and no blueshift is observed experimentally. To eliminate the blueshift and screen the electric field, we speculate that electrons in the quantum well are trapped in localized states.
Keywords
This publication has 36 references indexed in Scilit:
- Photoluminescence of InGaN/GaN and AlGaN/GaN multiple quantum well structures: role of depletion fields and polarization fieldsphysica status solidi (a), 2003
- Improved brightness of 380 nm GaN light emitting diodes through intentional delay of the nucleation island coalescenceApplied Physics Letters, 2002
- Direct measurement of piezoelectric field in In0.23Ga0.77N/GaN multiple quantum wells by electrotransmission spectroscopyJournal of Applied Physics, 2002
- Quantized states inheterostructures and the model of polarized homogeneous quantum wellsPhysical Review B, 2000
- Piezoelectric Polarization in GaInN/GaN Heterostructures and Some Consequences for Device DesignJapanese Journal of Applied Physics, 2000
- Depletion region effects in Mg-doped GaNJournal of Applied Physics, 2000
- Optical properties of InGaN quantum wellsMaterials Science and Engineering B, 1999
- Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructuresJournal of Applied Physics, 1999
- Intra- and interwell transitions in GaInN/GaN multiple quantum wells with built-in piezoelectric fieldsApplied Physics Letters, 1999
- Determination of piezoelectric fields in strained GaInN quantum wells using the quantum-confined Stark effectApplied Physics Letters, 1998