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arXiv · 1708.04752

Terahertz spectroscopy of an electron-hole bilayer system in AlN/GaN/AlN quantum wells

H. Condori Quispe·S. M. Islam·S. Bader·A. Chanana·K. Lee·R. Chaudhuri·A. Nahata·H. G. Xing·D. Jena·B. Sensale-Rodriguez
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Abstract

We describe studies on the nanoscale transport dynamics of carriers in strained AlN/GaN/AlN quantum wells: an electron-hole bilayer charge system with large difference in transport properties between the two charge layers. From electronic band diagram analysis, the presence of spatially separated two-dimensional electron and hole charge layers is predicted at opposite interfaces. Since these charge layers exhibit distinct spectral signatures at terahertz frequencies, a combination of terahertz and far-infrared spectroscopy enables us to extract (a) individual contributions to the total conductivity, as well as (b) effective scattering rates for charge-carriers in each layer. Furthermore, by comparing direct-current and terahertz extracted conductivity levels, we are able to determine the extent to which structural defects affect charge transport. Our results evidence that (i) a non-unity Hall-factor and (ii) the considerable contribution of holes to the overall conductivity, lead to a lower apparent mobility in Hall-effect measurements. Overall, our work demonstrates that terahertz spectroscopy is a suitable technique for the study of bilayer charge systems with large differences in transport properties between layers, such as quantum wells in III-Nitride semiconductors.

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H. Condori Quispe, S. M. Islam, S. Bader, A. Chanana, K. Lee, R. Chaudhuri, A. Nahata, H. G. Xing, D. Jena, B. Sensale-Rodriguez. 2017-08-16. Terahertz spectroscopy of an electron-hole bilayer system in AlN/GaN/AlN quantum wells. https://doi.org/10.1063/1.4996925

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