title: Interband impact ionization and nonlinear absorption of terahertz radiation in semiconductor heterostructures.
abstract: We have theoretically investigated nonlinear free-carrier absorption of terahertz (THz) radiation in InAs/AlSb heterojunctions. By considering multiple photon process and conduction-valence interband impact ionization (II), we have determined the field and frequency dependent absorption rate. It is shown that (i). electron-disorder scatterings are important at low to intermediate field, and (ii). most importantly, the high field absorption is dominated by II processes. Our theory can satisfactorily explain a long-standing experimental result on the nonlinear absorption in the THz regime.
authors.affiliation: State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, People's Republic of China.
authors.forename: J C
authors.initials: JC
authors.lastname: Cao