A dielectrically isolated photodiode array by silicon-wafer direct bonding

A dielectrically isolated silicon photodiode array was successfully fabricated by a silicon-wafer direct-bonding method. A thermally oxidized wafer and another bare silicon wafer were placed in close contact at room temperature and bonded by heat treatment at 1100°C applied for 4 h. A series-connected 23-photodiode array, with a 1.6 × 1.6-mm chip size, produced a 13-V open-circuit voltage and a 7.7-µA short-circuit current at a 10-mA GaAlAs infrared-light-emitting diode current. Enough voltage was obtained to drive power MOSFET's for switching applications, photocoupled solid-state relays, and other uses.