Monolithic integration of a photodiode and a field-effect transistor on a GaAs substrate by molecular beam epitaxy

Abstract

A Schottky barrier photodiode and a field-effect transistor (FET) have been monolithically integrated on a GaAs substrate using molecular beam epitaxy. The electronic isolation between constituent elements has been achieved by the present device structure in which a semi-insulating substrate is used. The dark current at the punchthrough voltage as low as 8×10−10 A and a uniform quantum efficiency over the photosensitive area have been observed by the measurements. A linear amplification of the photocurrent by the FET over a wide range of incident light power has been confirmed. The amplification ratio of 19 has been achieved with a 10-kΩ photodiode load resistor. The present result demonstrates the usefulness of molecular beam epitaxy in realizing optoelectronic integrations.