UV-specific (320-365 nm) digital camera based on a 128x128 focal plane array of GaN/AlGaN p-i-n photodiodes

An ultraviolet-specific (320-365 nm) digital camera based on a 128x128 arra y of backsideilluminated GaN/AlGaN p-i-n photodiodes has been successfully developed. The diode structure consists of a base n-type layer of AlGaN (si milar to 23% Al) followed by undoped and then p-type GaN layers deposited b y metal organic vapor phase epitaxy. Double-side polished sapphire wafers s erve as transparent substrates. Standard photolithographic, etching, and me tallization procedures were employed to fabricate the devices. The fully-pr ocessed photodiode array was hybridized to a silicon readout integrated cir cuit (ROIC) using In bump bonds for electrical contact. The UV camera was o perated at room temperature at frame rates ranging from 15 to 240 Hz. A var iety of UV scenes were successfully recorded with this configuration.