Pixelless 1.5-μm up-conversion imaging device fabricated by wafer fusion

We designed and fabricated a first-ever pixelless optical up-conversion imaging device using wafer-fusion technology. The device consists of an In/sub 0.53/Ga/sub 0.47/As-InP p-i-n detector and a GaAs-AlGaAs light-emitting diode (LED), which were grown on an InP and a GaAs substrate, respectively, and wafer-bonded together. The layer structures and doping profiles of the common region linking the detector and LED were designed such that lateral carrier diffusion was successfully suppressed while effective electrical connection was well preserved. Pixelless up-conversion imaging from 1.5 to 0.87 μm was demonstrated. Moreover, an internal electrical gain of over 100 was observed for the detector part of the integrated device. The internal up-conversion quantum efficiency was measured to be /spl sim/50% at room temperature.