Persistent-photoconductivity effect in δ-dopedAl0.48In0.52As/Ga0.47In0.53As heterostructures
| Autor: | M. Ahoujja, D. P. Wang, W. C. Mitchel, J.-P. Cheng, H. Hier, K. Y. Hsieh, Ikai Lo, T. F. Wang, A. Fathimulla |
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| Rok vydání: | 1995 |
| Předmět: | |
| Zdroj: | Physical Review B. 52:14671-14676 |
| ISSN: | 1095-3795 0163-1829 |
| DOI: | 10.1103/physrevb.52.14671 |
| Popis: | We have studied the electronic properties of \ensuremath{\delta}-doped ${\mathrm{Al}}_{0.48}$${\mathrm{In}}_{0.52}$As/${\mathrm{Ga}}_{0.47}$${\mathrm{In}}_{0.53}$As heterostructure samples by Shubnikov--de Haas and quantum-Hall-effect measurements. The well-defined two-subband occupied two-dimensional electron gas was detected. From the Fermi level at these two subbands, we calculate the energy difference between the lowest two subbands' minima to be 54 meV. After illuminating the sample at low temperature, we did observe a persistent photoconductivity. The electron densities of the first and second subbands for the sample with preannealed substrate were increased by the illumination from 17.3 to 18.2\ifmmode\times\else\texttimes\fi{}${10}^{11}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ and 3.6 to 4.1\ifmmode\times\else\texttimes\fi{}${10}^{11}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$, respectively. The onset of the second subband occurs at ${\mathit{n}}_{0}$=10.3\ifmmode\times\else\texttimes\fi{}${10}^{11}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$. We also found that the concentration of deep donor traps is about 1.4\ifmmode\times\else\texttimes\fi{}${10}^{11}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ and the deep donor traps are not affected by the preannealed substrate. We believe that the model to describe the persistent-photoconductivity effect in semiconductor heterostructure samples needs to be extended to those deep donor levels below Fermi energy and it does not have to be the DX center. |
| Databáze: | OpenAIRE |
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