Research propels quantum dots forward

The challenges faced by the quantum-dot IR photodetectors (QDIP), which are well-suited for detecting mid-IR light at elevated temperatures, are discussed. The quantum-mechanical nature of the QD for IR photodetectors allows normal-incidence detection, large excited-state electron relaxation times for increased detector efficiency, several tuning parameters for controlling optoelectronic properties, and low dark currents for HOT IR photodetection. Electrons can be introduced in the QD by direct doping, modulation doping, or capture of injected electrons from the device contact. However, it is a challenge to control this dopant incorporation during the Stranski-Krastanow (S-K) growth, used to synthesize active-region heterostructures such as QDs.