Electrical characteristics of buried-Pt Schottky contacts on thin InP/InAlAs heterostructures

Schottky diodes were fabricated on the InP/InAlAs heterostructures where the thickness of the InP ranges from 0 to 7 nm. A Ne-based atomic layer etching technique was utilized for precise control of the thickness of the InP layer. After removing the part of the InP layer, Pt/Ti/Pt/Au multilayer metallization was evaporated to form a Schottky contact. Thermal annealing was then carried out to drive Pt into the device layer. The electrical characteristics of the Schottky diodes were analyzed to determine the effect of a thin InP layer on the performance of the Schottky diodes. Transmission electron microscopy (TEM) was also utilized to investigate the diffusion of the metal into the semiconductor heterostructures. The experimental results show that the 7-nm-thick Pt can pass through the 4-nm-thick InP layer and reach the InAlAs layer. A Schottky junction was effectively formed within InAlAs layer when the thickness of the InP layer was equal or less than 4 nm for the 7-nm-thick Pt bottom layer.