Electrical characterization of InAs/GaAs quantum-dot infrared photodiodes

Abstract

The electrical properties of InAs/GaAs quantum-dot infrared photodiodes (QDIP) were characterized by capacitance-voltage and deep-level transient spectroscopy measurements. The QDIP structures with self-assembled quantum dots (SAQDs) were grown in atomic layer epitaxy mode by using a molecular beam epitaxy method. The samples had five-stacked SAQD layers on n(+)-GaAs substrates. In Si-doped InAs/GaAs QDIP structures, two electron deep levels of E-C-0.52eV with an emission cross section of 2.3 x 1.0(-15) cm(2) and E-C-0.57 eV with 4.5 x 10(-16) cm(2) were observed by DLTS measurements. These two levels are associated with the excited and the ground states in the QD layers, respectively, and are in good agreement with the PL results. An interface state on the low-energy side was also measured, and this may be a source of leakage current.