Design of photoelectric convertors on the basis of Si-Ge solid solutions

Abstract

Electric and photoelectric properties of Si1-xGex<Hf> (x=0.1) whiskers were investigated. The whiskers were grown by method of chemical transport reactions in closed Si-Ge-Au-Hf-Br system. Concentration of Hf in whiskers is 1,6⋅10-2 3, concentration of Au is 10-3 3. The samples have n-type conductivity; their resistivity ρ changes from 0.5 to 12 Ω⋅cm depending on the whisker diameter. The whisker diameters change from 10 to 80 µm, the whisker length is equal to 0,5÷5 mm. The whiskers were shown to be photosensitive both in photovoltaic and in photoresistive regimes. Photo-e.m.f. value is about 100 mV in the whisker with small diameter (d=20 µm) and it decreases at a rise of the whisker diameters from 20 to 80 µm. Appearance of photo-e.m.f. is caused by existance of Shotki barrier in SiGe-Pt contact to the whiskers. Dimensional effect of the whisker photo-e.m.f. is explained by the dimensional dependence of the whisker resistivity. High values of photo-e.m.f. for Si-Ge <Hf> whiskers allow their using for photoconvertor design.