Fabricating quantum dot infrared photodetectors (QDIPs) operable under high temperatures has remained a challenge. The authors report the performance of multispectrum 35-layer In0.50Ga0.50As/GaAs QDIP at high temperatures. Results showed three photoresponse peaks at ∼5.6, 7.4, and 11.5 μm. The third peak is observed only at 200 K, possibly because of transition of electrons from the second excited state of the quantum dot to GaAs barrier state. Peak responsivity value (∼140 mA/W) and maximum D* value (∼1.25 × 1010 cm·Hz1/2/W) is reached at 1.5 V. Responsivity is higher (210 mA/W) at 150 K than 77 K, possibly because of better transport of carriers at higher temperatures. The D* values are ∼4.33 × 108 cm·Hz1/2/W at 150 K and ∼3.3 × 106 cm·Hz1/2/W at 200 K at 1.0 V bias. © 2013 American Vacuum Society.