Effect of AlGaAs cladding layer on GaInNAs/GaAs MQW p-i-n photodetector

The electronic properties of GaInNAs/GaAs multiple-quantum-well (MQW) p-i-n photodetector with AlGaAs cladding layer have been studied. By applying a higher band gap Al_0.3Ga_0.7As to the photodetector, a substantial reduction in dark current was observed owing to an inherent difficulty for holes to surmount the high potential barrier between MQW and the cladding layer heterojunction under a reverse bias. The dark current obtained was as low as 4.1 pA at -3.5 V for a device with Al_0.3Ga _0.7As cladding layer as compared to 22 μA also at -3.5 V for a similar device without the Al_0.3Ga_0.7As cladding layer. The photo/dark current contrast ratios obtained were 4.2×10⁴ and 11, respectively, for devices with and without an Al_0.3Ga _0.7As cladding layer at -3.5 V. In addition, peak responsivity of 1 mA/W was measured at around 1150 nm. Two orders of magnitude increase in the rejection ratio were realized between 1150 and 1250 nm at -2.0 V. The GaInNAs/GaAs MQW p-i-n photodetector was demonstrated with the AlGaAs cladding layer potentially providing a higher photo/dark current contrast ratio and higher responsivity rejection ratio.