Many-body effects in quantized semiconductor electron accumulation layers
Lead Research Organisation:
University of Warwick
Department Name: Physics
Abstract
While most materials have an absence of charge carriers at their surface, a number of semiconductors have been discovered which can support a large build up of electrons at the surface. This creates a potential well at the surface of the semiconductor, causing the conduction band states to become quantized into two-dimensional subbands. We will employ high-resolution angle resolved photoemission spectroscopy (ARPES) measurements of these quantized states in the technologically important materials, InAs, InSb, InN, and ZnO, in conjunction with complementary angle integrated photoemission spectroscopy measurements and bulk electrical and optical studies. While often treated in a one-electron picture, solids are immensely complex many-body systems where processes such as electron-electron (e-e) and electron-phonon (e-ph) interactions can lead to a pronounced renormalization of the material's electronic structure, which can prove essential in determining their fundamental properties. Such effects have hitherto been neglected in the study of these quantized electron accumulation layers. Using ARPES, we will perform a detailed characterisation of the many-body processes in these systems, including their dependence on factors such as temperature, the electron density within the quantum well, and the effective mass and Debye temperature of the host material. This feasibility study will not only develop a thorough understanding of quantized semiconductor electron accumulation layers, important for application of these technologically important materials, but also intends to demonstrate their use as model systems for investigating fundamental features of many-body interactions in solids. Consequently, it has implications for understanding the electronic properties of a wide range of solids, including not only semiconductors but also, for example, metals, highly-correlated electron materials and high-Tc superconductors.
Publications
Allen M
(2010)
Bulk transport measurements in ZnO: The effect of surface electron layers
in Physical Review B
King PD
(2010)
Surface band-gap narrowing in quantized electron accumulation layers.
in Physical review letters
Allen M
(2011)
Polarity effects in the x-ray photoemission of ZnO and other wurtzite semiconductors
in Applied Physics Letters
Zhang K
(2011)
Thickness dependence of the strain, band gap and transport properties of epitaxial In 2 O 3 thin films grown on Y-stabilised ZrO 2 (111)
in Journal of Physics: Condensed Matter
Vasheghani Farahani S
(2011)
Electron mobility in CdO films
in Journal of Applied Physics
Vasheghani Farahani S
(2012)
Influence of charged-dislocation density variations on carrier mobility in heteroepitaxial semiconductors: The case of SnO 2 on sapphire
in Physical Review B
Vasheghani Farahani S
(2013)
Impact of degenerate n -doping on the optical absorption edge in transparent conducting cadmium oxide
Vasheghani Farahani S
(2013)
Temperature dependence of the direct bandgap and transport properties of CdO
in Applied Physics Letters
Vasheghani Farahani S
(2014)
Valence-band density of states and surface electron accumulation in epitaxial SnO 2 films
in Physical Review B
Park D
(2014)
Optimal growth and thermal stability of crystalline Be0.25Zn0.75O alloy films on Al2O3(0001)
in Applied Physics Letters
Description | Identified the existence of quantum confined states in a 2-dimensional electron gas at the surface of the transition metal oxide CdO |
Exploitation Route | This work was the first to identify this phenomenon and has since been explored in other oxide materials - including several use in photovolaics |
Sectors | Electronics,Energy |