EFFECT OF IR IRRADIATION ON THE SURFACE-PROPERTIES OF CDXHG1-XTE SOLID-SOLUTIONS

The effect of IR irradiation on the surface properties of CdxHg1-xTe ( x = 0.21-0.22) solid solutions is investigated. IR excitation reduces the net adsorption activity of the material owing to photodesorption o f weakly bound species. More strongly bound species remain adsorbed on the surface for fairly long periods of time after irradiation, thereb y providing evidence for irreversible chemisorption. The surface condu ctivity of the material typically rises under IR irradiation. The mech anisms responsible for dark adsorption and photoadsorption-photodesorp tion of hydrogen, oxygen, and carbon dioxide molecules are considered. Repeated irradiations of the material give rise to the formation of a dditional structural defects, which act as electron donors or accepter s, and, accordingly, to changes in the charge of ionic species formed during adsorption. These processes are also accompanied by rearrangeme nt of surface atoms and type conversion.