Ga0.47In0.53As vertical photoconductive detectors with high gain and low bias voltage

We demonstrate for the first time a long-wavelength Ga0.47In0.53As vertical photoconductive detector with very high gain, low noise, low-bias voltages, high sensitivity, and high-coupling efficiency. The detector consists of an n+InP, a Fe-doped Ga0.47In0.53As, and an n+Ga0.47In0.53As layer grown successively on a semi-insulating InP substrate. The highly resistive active layer sandwiched between two n+layers creates a uniform electric field perpendicular to the surface, producing a dc gain of 86 at bias voltages as low as 0.5 V. The noise power at 100 MHz is about 11 dB lower than that of a coplanar interdigitated photoconductive detector prepared with undoped GaInAs grown by vapor-phase epitaxy. Preliminary measurements reveal a receiver sensitivity of -28.2 dBm at a bit-error rate of 10^-9at 420 Mbit/s and a wavelength of 1.55 µm.