In As ∕ Ga As quantum-dot infrared photodetectors grown by molecular beam epitaxy

We have studied InAs∕GaAs quantum-dot photodetectors containing 50 periods of quantum-dot layers. Clean photoresponse spectra and a peak responsivity of about 99mA∕W are observed up to about 120K. The device structures contain no (Al, Ga)As current-blocking layers. A relatively low dark current and a high peak responsivity (0.242A∕W) are observed at 78K. These results suggest that increasing the dot density, controlling the dopant impurity concentration, and incorporating a current-blocking layer would most likely increase the operating temperature of the devices beyond 120K.