The Photoexcited Flow of Nonequilibrium Phonons along a Crystal Surface

Abstract

It is shown, that for a light beam of oblique incidence to the crystal surface, a nonequilibrium phonon flux along the surface can exist. The transverse acoustic phonons of the lower branch of spectrum whose free path length is large a t low temperatures give the main contribution to the flow. Such phonons arise either immediately a t infrared absorption or as the result of the decay of optical and longitudinal acoustic phonons. The phonon energy flux is calculated and shown to be of the same order of magnitude as the incident light flux. The phonon-electron drag current in the metal film bordering the unexposed surface of the dielectric is considered. nOKa3aH0, 9 T O npH HaIEJIOHHOM HaxeHHIT CBeTOBOrO ny9Ka Ha IIOBepXHOCTb IcpHCTaJIJIa B03MO)KeH TIOTOK (POHOHOB BgOJIb JIOBepXHOCTH. OCHOBHOR BIcJIaA B IIOTOK AamT no-lleperHbIe aKyCTHqeCKHe (POHOHbI H H m H e t BeTBH CneRTpa, KOTOpbIe IIpH HUBKHX TeM-nepaTypax EiMeIOT ~O J I M I I~I O AJIIIHY CBO60~HOrO npo6era. Tame @OHOHbI IIORBJIRIOTCR HaK HenocpeAcTBeHHo npu IrH@paHpacHoM nornoueHEia cBeTa, Tag I I npx pacrranax OIITHrecxlix li npoaonbHbIx aIcycTmecHux (POHOHOB. HalxeHa Beamma noToKa a~e p r~~ GOHOHOB li nOKa3aH0, 9 T O OHa HMeeT nOpRAOK BeJIH'IBHbI lSaHaIO4erO CBeTOBOrO IIOTOKB. BbmiCJreH TOK @OHOH-3JIeKTPOHHOrO yBJIe9eHHR B MeTaJIJIH9eCKOH nJIeHKe, K' paHHqawefi C HeOCBeIL(€!HHOfi IIOBepXHOcTbIO AH3JIeKTPHKa. 1) Prospekt Akademika Lavrenteva 13, 630090 Novosibirsk, USSR. 2, For electrons the phenomenon like this is called surface photogalvanic effect [4].