Dark current and band profiles in low defect density thick multilayered GaAs/InAs self-assembled quantum dot structures for infrared detectors.

We report results of a systematic study of the structural and photoresponse properties of GaAs/{InAs quantum dot (QD)/InGaAs quantum well/GaAs} ×m multiple quantum dot (MQD) structures with m from 1 to 20 placed in n-GaAs/i(MQD)/n-GaAs configuration to act as quantum dot infrared photodetectors (QDIPs). Extremely low dislocation densities inferred from cross-sectional and plan-view transmission electron microscopy and the observed linear increase in photoluminescence intensity with MQD thickness reveal the high quality of these QDIP structures. Temperature and bias dependent dark and photocurrent measurements reveal dark current activation energies (E_a) increasing with the number of QD layers in a manner that indicates that E_a represents the built-in potential in the MQD region. These studies indicate the need for more quantitative modeling to guide optimal doping strategies and profiles to realize high photocurrents while maintaining acceptable dark current. [ABSTRACT FROM AUTHOR]