We have studied InAs/GaAs quantum-dot photodetectors containing 50 periods of quantum-dot layers. Clean photoresponse spectra and a peak responsivity of about 99 mA/W are observed up to about 120 K. The device structures contain no (Al; Ga)As current-blocking layers. A relatively low dark current and a high peak responsivity(0.242 A/W) are observed at 78 K: 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 120 K. (c) 2006 American Vacuum Society.