Influence of modulation doping on p-i-p quantum-dots (InAs/GaAs)-based infrared detector performance

Abstract

Quantum dots based infrared photodetectors (QDIPs) having intra-valence band transitions and holes as majority carriers have been explored in this work. Here, we are demonstrating the effect of modulation doping on p-i-p QDIP (InAs/GaAs) grown using molecular beam epitaxy (MBE). The active region of the detector consists of 10 layers of selfassembled InAs quantum dots (2.7 ML) capped with GaAs layers and embedded in between p-type (beryllium-doped) GaAs layers. The performance of InAs/GaAs p-i-p QDIP (device A) was compared with modulation doped InAs/GaAs QDIP (device B). In the case of device B, modulation doping with p-type GaAs was introduced after growing 7nm of GaAs capping. The ground state emission peak at 10 K from photoluminescence spectroscopy was measured at 1060.5 nm and 1055.5 nm with a thermal activation energy of 222.93 meV and 157.57 meV for sample A and B, respectively. The measured dark current density at 75 K was 0.448 and 1.012 A/cm2 at -1 V for device A and B, respectively. Spectral response peak in short wave infrared region (1.5 to 2.5 μm) were observed from both devices but in the case of device B, the spectral peaks were visible in mid wave infrared regime as well. At 75 K, the peak responsivity value measured was 35.11 A/W (at -1.5 V) and 0.333 A/W (at -1.5 V bias) for device A and B, respectively. High temperature of operation upto 200 K was observed from Device A whereas Device B exhibited response up to 125 K. Modulation doping close to the InAs quantum dots deteriorates the device performance.