1 February 2007 Studies of the critical electric field and L valley offset of a semiconductor characterized by terahertz radiation
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Abstract
The amplitudes of terahertz radiation are measured for a series of GaAs surface intrinsic-n+ (SIN+) structures with various built-in surface electric fields as the bias. As the surface field is lower than the so-called "critical electric field" related with the energy difference between the &Ggr; to L valley of the semiconductor, the amplitude is proportional to the product of the surface field and the number of photo-excited carriers. As the intensity of surface field exceeds the critical field, the THz amplitude is independent of the surface field but proportional the number of the photo-excited carriers. Our study proposed two optimal conditions for an SIN+ structure to serve as a THz emitter: the width of its intrinsic layer is nearly equal to the penetration depth of the pump beam, and the intensity of built-in electric field is nearly equal to the critical electric field. Notably, the critical field determined from the THz amplitude under various electric fields provides one way to estimate the &Ggr; to L valley splitting in semiconductors.
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J. S. Hwang, J. S. Hwang, H. C. Lin, H. C. Lin, C. K. Chang, C. K. Chang, T. S. Wang, T. S. Wang, K. L. Lin, K. L. Lin, L. S. Chang, L. S. Chang, Y. T. Lu, Y. T. Lu, } "Studies of the critical electric field and L valley offset of a semiconductor characterized by terahertz radiation", Proc. SPIE 6472, Terahertz and Gigahertz Electronics and Photonics VI, 647203 (1 February 2007); doi: 10.1117/12.700142; https://doi.org/10.1117/12.700142
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