Study of electrically excited gallium arsenide as a terahertz gain medium

• Main Authors: Wu, Ming-Chi, 吳明錡
• Other Authors: Yen, Shun-Tung
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/86704492662583527412

碩士 === 國立交通大學 === 電子工程學系 電子研究所 === 102 === In this thesis, we study the possibility of obtaining terahertz gain through population inversion between phonon states in semi-insulating gallium arsenide crystals. Phonons are excited by applying voltage biases to the crystals under controlled and uncontrolled heat sink conditions. Variations of phonon population are probed by measuring bias-dependent reflection spectra. In uncontrolled heat sink experiments, we find the phonon population of an electrically excited crystal differs greatly from that of a crystal under thermal equilibrium in the spectral region where two-phonon sum processes dominate. In controlled heat sink experiments, we do not observe obvious spectral changes with biases. The results indicate that the sink extracts the excited phonons effectively but unselectively. In both heat sink conditions, we do not observe evidence of population inversion between phonon states from reflectance spectra in the spectral region dominated by two-phonon difference processes.