ANALYSIS OF THE ACTIVE LAYER IN SI GAAS SCHOTTKY DIODES

The behavior of the active region width W of semi-insulating gallium a rsenide Schottky diodes versus reverse biasing has been investigated b y optical beam induced current and surface potential techniques. It ha s been found that at low applied voltages, W follows the square root l aw peculiar to a Schottky barrier while, for a bias higher than 20 V, the active layer increases linearly with the voltage applied. To go de eper into this matter, the spatial distribution of the electric field has been analyzed in a wide range of bias voltages and it has been obs erved that at high voltages a plateau occurs, followed by a linear dec rease down to a quasi-zero value. In terms of space charge distributio n this means that there is a box-shaped space charge region moving tow ards the ohmic contact at increasing bias. (C) 1998 Published by Elsev ier Science B.V. All rights reserved.