Ultra-fast, High Saturation Current, InGaAs/InP Photodetectors

In Phase I, we propose to develop high saturation current photodiodes that will meet the following design criteria: (a) Responsivity > 0.7 A/W, (b) 1 dB compression current > 100 mA, (c) Bandwidth > 10 GHz, and (d) Wavelength response of 1300 to 1550 nm. Two different photodiode designs will be tested for maximum saturation current: Partially Depleted Absorber (PDA) and Charge Compensated Uni Traveling Carrier (CC UTC). A comparative study of these two designs will determine which structure is more suitable for the above design goals. As saturation current levels increase above 100 mA, the problem of excessive Joule heating (multiple of voltage bias and photodiode current) creates the problem of "thermal runaway" leading to eventual device failure. We will investigate "wafer bonding" of InGaAs photodiodes to silicon wafers for better heat removal caused by Joule heating. This will ultimately lead to a more reliable photodiode. In a potential Phase II, we will expand the bandwidth of the photodiodes to 100 GHz with current saturation limit up to 50 mA.