64x1 UV focal plane array of GaN p-i-n photodiodes

In recent years, AlxGa1-xN semiconductor alloys, with a direct bandgap tunable between 3.4eV and 6.2eV, become the most suitable materials for the fabrication of UV detectors. In this paper we describe the fabrication and characteristics of an UV 64x1 focal plane array (FPA) based on front illuminated GaN p-i-n photodiodes. The diode structure consists of a base n-type layer of GaN followed by unintentionally doped and p-type layers deposited by metal organic chemical vapor deposition on GaN buffered sapphire substrate. Standard photolithographic, Ar+ ion beam etching, SiO2 passivation and metallization procedures were employed to fabricate the devices. I-V, responsivity and spectral response were tested. The. linear photodiode array was indirectly hybridized to a silicon readout integrated circuit (ROIC) chip. The ROIC chip consists of capacitor feedback transimpedance amplifier (CTIA) input circuits, correlated double sampling (CDS) circuits, shift registers etc. The 64x1 UV linear FPA was packaged into a 28-pin chip carrier. The response ununiformity is 1.86%. The mean detectivity is about 2.0x10(9)cmHz(1/2)W(-1).