Normal incidence InAs/AlxGa1-xAs quantum dot infrared photodetectors with undoped active region

We have performed a comprehensive investigation of n-type quantum dot infra red photodetectors (QDIPs) based on InAs/GaAs epitaxical island quantum dot s (QDs) grown via the innovative punctuated island growth technique. The st ructural properties of the QDs were investigated with cross-sectional trans mission electron microscopy and atomic force microscopy. The electronic pro perties of the QDs inserted in QDIP devices were investigated with photolum inescence (PL), PL excitation, and intra- and inter-band photocurrent spect roscopy. The influence of AlGaAs layers inserted into the QDIP active regio ns on the performance of dark current and inter- and intra-band photocurren t was examined. Initial results on intra-band responsivity and detectivity of these QDIPs at 77 K with undoped active region show promise for applicat ion. (C) 2001 American Institute of Physics.