title: The dependence of terahertz radiation on the built-in electric field in semiconductor microstructures.
abstract: The amplitudes of terahertz radiation are measured for a series of GaAs surface intrinsic-N(+) 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 Gamma 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 surface field exceeds the critical field, the amplitude is independent of the surface field but proportional to the product of the critical field and the number of the photo-excited carriers.
authors.affiliation: Dept. of Physics, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan, Taiwan 70101.
authors.forename: Jenn-Shyong
authors.initials: JS
authors.lastname: Hwang
authors.forename: Hui-Ching
authors.initials: HC
authors.lastname: Lin
authors.forename: Chin-Kuo
authors.initials: CK
authors.lastname: Chang
authors.forename: Tai-Shen
authors.initials: TS
authors.lastname: Wang
authors.forename: Liang-Son
authors.initials: LS
authors.lastname: Chang
authors.forename: Jen-Inn
authors.initials: JI
authors.lastname: Chyi
authors.forename: Wei-Sheng
authors.initials: WS
authors.lastname: Liu
authors.forename: Shu-Han
authors.initials: SH
authors.lastname: Chen
authors.forename: Hao-Hsiung
authors.initials: HH
authors.lastname: Lin
authors.forename: Po-Wei
authors.initials: PW
authors.lastname: Liu