Wet-chemistry surface treatment for dark-current reduction that preserves lateral dimensions of reactive ion etched Ga/sub 0.47/In/sub 0.53/As p-i-n diode photodetectors

摘要

A wet-chemistry treatment, consisting of a fresh mixture of one-to-one 2-propanol plus concentrated sulfuric acid added to photoresist developer, which is tetramethyl ammonium hydroxide, was found to reduce the dark-current density at the -5-V dc reverse-bias to 2 pA//spl mu/m/sup 2/ (2/spl times/10/sup -4/ A/cm/sup 2/), and simultaneously to maintain the lateral geometrical dimensions, of reactive ion etched, 3 micrometer tall, right-cylinder mesa, Ga/sub 0.47/In/sub 0.53/As p-i-n diode photodetectors with diameters of 100, 50, and 25 /spl mu/m.