Improvement in operating temperature of InAs/GaAs quantum-dots-based photodetectors by varying position of localized carriers in active region

Modulation doping or localization of carriers in the detector or solar cell structure is an interesting technique which has piqued the interest of researchers. In this study, we demonstrate the effect of modulation doping on InAs/GaAs p-i-p QDIP grown on semi-insulating GaAs substrate using MBE. The active region consists of 10 layers of 2.7 ML InAs quantum dots followed up with 60 nm GaAs capping layer. In the GaAs capping, a modulation p-doping of 3 nm was introduced at 7, 12 and 17 nm from the InAs dot layer thus forming sample A, B and C, respectively. The ground state emission peak at 19 K from photoluminescence (PL) spectroscopy was measured at 1055.5, 1057.5 and 1062 nm for sample A, B and C respectively. Activation energies calculated from temperature dependent PL spectra were 157.57, 167.18 and 146.63 meV for the respective samples. The fabricated single pixel detectors exhibited spectral response peak from 1 to 3.5 μm in short wave infrared (SWIR) region for all the samples. The spectral response peaks observed were at 2.01 and 2.43 μm for device A, at 1.83 μm for device B and at 1.77 μm for device C. Highest operating temperature obtained from device A, B and C were 100K, 150K and 200K, respectively. The peak responsivities observed at 100K were 0.503, 0.154 and 0.33 A/W for the device A, B and C, respectively. Optimizing the position of localized carriers introduced in the active region can achieve the tunability in detection peak.