SILICON DIOXIDE PASSIVATION OF IN P INGAAS METAL-SEMICONDUCTOR-METAL PHOTODETECTORS/

We report on passivation and antireflection coating of InP/InGaAs meta l-semiconductor-metal photodetectors by low-temperature deposited sili con dioxide. The passivating performance of silicon dioxide films appl ied by nonreactive radio frequency magnetron sputtering and remote pla sma enhanced chemical vapor deposition are comparatively investigated. Different wet chemical treatments Of the InP surface prior to deposit ion including sulfur passivation are performed and their influences on the device performance are presented. Under optimized deposition cond itions and pretreatments, both processes result in a stable and reprod ucible surface passivation as reflected by a drastic reduction of exce ssive leakage currents and photocurrent gain. The improvement of the d evice characteristics due to the silicon dioxide coating is attributed to a substantial lowering of the density of interface states at the i nsulator-InP interface as compared to nonpassivated devices. (C) 1996 American Vacuum Society.