Long wavelength infrared absorption characteristics of an ln(0.3)Ga(0.7)As/GaAs quantum well infrared photodetector (QWIP) employing an n-i-p-i-n camel diode structure were compared with those of a conventional n-QWIP. QWIPs showed a photocurrent response peak at the wavelength of approximately 10 mum due to electronic intersubband transitions in quantum wells. The QWIP employing the camel diode structure showed a reduced dark current. an increased responsivityrid thus all improved detectivity compared with those of the conventional n-QWlP due to the presence of the n-i-p-i-n camel barrier. The results indicated the potential of the QWIP employing an n-i-p-i-n camel diode structure for use in infrared detectors operating at elevated operating temperature. (C) 2002 Elsevier Science Ltd. All rights reserved.