Operation of suspended lateral SOI PIN photodiode with aluminum back gate

In this paper, we report a lateral silicon-on-insulator (SOI) P+P-N+ (PIN) photodiode suspended on a micro-hotplate platform, with aluminum (Al) layer deposited on backside. Voltage applied to the Al back gate can modify the depletion condition in the intrinsic (I) region. The device output photocurrent reaches a maximum under fully-depleted (FD) condition achieved by the positive back-gate bias. Moreover, the backside Al acts as a excellent reflector, which for specific wavelength ranges (around 500, 600, 770 nm) significantly boosts optical response of the SOI PIN photodiode. Over 2~3× improvements of responsivity (up to R = 0.1 A/W at 590 nm) have been achieved and validated in the measurements at 490, 590, 760 nm. Full optoelectronic two-dimensional (2-D) device simulations are conducted in Atlas software to comprehensively validate the device performance and improvement.