Demonstration of a Novel Mid Infrared Device: The Quantum-Dot Avalanche Photodiode (QDAP)

摘要

Mid-infrared photodetectors, operating in the 50-400meV (3-25μm) regime, have a variety of potential applications in medical diagnostics, thermal imaging, night vision cameras for battlefield recognition systems, and chip-based detection of chemical warfare agents. Intersubband quantum dot detectors have been proposed as a promising technology due to their normal incidence excitation and lower dark currents. However, the low quantum efficiency leads to a lower detectivity, responsivity and limits their operating temperature to about 70-80K. In this paper we demonstrate an intersubband quantum dot detector coupled to an avalanche photodiode to improve the signal-to-noise ratio and increase the operating temperature of the device. The heterostructure of the proposed device called Quantum Dot Avalanche Photodiode (QDAP) is shown in Fig. 1. An n-i-n intersubband DWELL detector is grown on top of a p-i-n avalanche photodiode (APD) structure in a single-step epitaxy. A p-n tunnel barrier is formed in the middle of the QDAP to enable injection of photogenerated electrons. During the device operation, the n-i-n and p-i-n regions of the device are both reverse biased (i.e., V{sub}(top)