InAs/GaAs p – i – p quantum dots‐in‐a‐well infrared photodetectors operating beyond 200 K

Abstract

High-temperature operating performance of p-i-p quantum dots-in-awell infrared photodetectors (QDIPs) is successfully demonstrated. The optically active region consists of 10 layers of p-doped selfassembled InAs quantum dots (QDs) asymmetrically positioned in In 0.15 Ga 0.85 As quantum wells (QWs). The dark current is suppressed by an incorporated superlattice (SL) structure composed of 10 pairs of AlGaAs/GaAs heterostructure. The very low recorded dark current makes the fabricated p-i-p QDIPs suitable for high-temperature operation. The measured photoresponse reveals broad mid-wave infrared (MWIR) detection up to 200 K. Introduction: Self-assembled InAs quantum dots (QDs) grown on GaAs have demonstrated excellent carrier confinement and δ-function-like density of states with important applications, including infrared photodetectors (IPs) and infrared sources [1][2][3]. In particular, InAs/GaAs QDIPs have been extensively investigated due to their advantageous properties, such as sensitivity to normal incident infrared radiation and weak thermionic coupling between the ground state and excited states, compared to quantum well IPs (QWIPs), resulting in reduced dark current. In the past few years, the intersubband photoresponse of n-type QD detector structures have been the subject of intense research [3-6]. However, high-temperature operation of n-type QDIPs has still remained a challenging problem although the hydrogenbased treatment processes were conducted to suppress the dark current [5,6]. However, complementary p-type QD detectors offer an interesting alternative detector design based on optical intra-valence band hole transitions. Such p-type QDIPs have recently attracted much attention not only due to the intermixing of heavy hole and light hole states enhancing the normal incidence absorption, but also due to the higher effective mass of holes lowering the dark current [7,8]. These interesting properties make them suitable for realising efficient low-cost and high-temperature operating photodetectors. Although recently reported InAs/GaAs p-type QDIPs indeed demonstrate higher quantum efficiency compared to present n-type QDIPs, they still suffer from larger dark current due to the absence of dark current blocking layers [8].In this Letter, we demonstrate high-temperature performance of p-type QDIPs composed of InAs QDs asymmetrically embedded in In 0.15 Ga 0.85 As QWs and AlGaAs/GaAs short-period superlattice (SPS) layers. Dark current and spectral photoresponse of the fabricated p-i-p QDIPs were characterised at different temperatures.

InGaAs/InP quantum well infrared photodetector integrated on Si substrate by Mo/Au metal-assisted wafer bonding

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