Floating-base InGaP/GaAs heterojunction phototransistors with low doped extrincsic base

Floating-base InGaP/GaAs heterojunction phototransistors (HPTs) with low doped extrinsic base region are demonstrated. Electrical and optical characteristics of the fabricated HPTs with and without SiN_x passivation are investigated. Moreover, the optical gain of these HPTs is compared in terms of variation of the emitter size. The SiN_x passivated HPTs with 50×50 μm² of emitter size showed the superior high optical gain. The devices exhibited very high optical gain of 159 at optical power of 100 nW under 635 nm illumination.