Dependence of thickness on avalanche characteristics of Te-doped amorphous selenium photoconductive target

Abstract

The thickness dependence of the avalanche characteristics of a tellurium (Te)-doped amorphous selenium (a-Se) high-gain avalanche rushing amorphous photoconductor (HARP) target is investigated. To improve the quantum efficiency of the a-Se HARP photoconductive target, a Te-doped a-Se photoconductive layer is sandwiched within a-Se HARP target. The avalanche multiplication factor and hole ionization coefficient of the a-Se HARP target are obtained using the result of photocurrent measurement. The multiplication factor in the avalanche mode exponentially increases with increasing electric field by avalanche multiplication phenomena over the threshold field. The quantum efficiency of the 8-μm-thick a-Se HARP target in the avalanche mode is higher than that of the thin HARP target below 2 μm thickness. Also the spectral response, decay lag, and light-transfer characteristics are studied. © 2009 The Japan Society of Applied Physics.