RESIST - Readout-ic for Extended SWIR Imaging Staircase-apd Technology

DoD has a clear established need for 2-micron cut-off APDs. However, the developments of such a device face the following problems: Due to the longer cut-off the band gap of these devices is narrow, leading to increased dark current. To overcome the dark current the APDs must be cooled making the systems expensive, bulky and power hungry. The APD gain mechanism has an increased statistical noise related to the gain mechanism. This noise is characterized by an excess noise factor. If this factor is high, the APDs cannot be operated at high gains as the excess noise limits the signal to noise ratio (SNR). HgCdTe (MCT) APDs have been demonstrated to have very low excess noise factor and a tunable bandgap to achieve extended SWIR cut-off. However, these APDs have very high dark current and are not as producible as III-V devices. This causes MCT FPAs to be expensive and the systems to be even more expensive due to cryogenic cooling requirements. To overcome the above limitation our team has developed a novel 2-micron cutoff APD. The staircase APD demonstrated by our team has the following advantages: It has low excess noise (