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

Abstract

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 (Ea) increasing with the number of QD layers in a manner that indicates that Ea 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.

Performance investigations of quantum dot infrared photodetectors

“…2a, the dark current density changes rapidly with the increase of the applied electric field, which can be mainly ascribed to the contribution of the microscale electron transport on the dark current density, whereas the subsequent slow increase of the dark current density reveals the significant contribution of the nanoscale electron transport. More importantly, our theoretical results obviously show a good agreement with the previous published experimental results [15] plotted with black squares at 77 K in Fig. 2a, which well directly examines the validity of our dark current density model.…”

“…Furthermore, it is very clear that Eq. (3) can be divided into two parts, E 0,micro exp (ÀE/E 0 ) corresponds to the activation energy under the microscale transport mechanism which is thermal emission over the effective potential barrier [15], and E 0,nano À bE indicates the activation energy under the nanoscale transport mechanism which means the escaping from quantum dots related to tunnelling [16,17]. Substituting Eq.…”

Optically Triggered Infrared Photodetector

“…However, they cannot, so far, compete in performance with their photodiode counterpart. 4 With that goal, big efforts are being made for achieving increased responsivities and lower dark currents [14][15][16] . The difficulty of this task lies in the dependency of both parameters with the applied voltage in voltage-driven photodetectors.…”

Review of current progress in quantum dot infrared photodetectors

“…Asano et al [145] pointed out the need for more qualitative understanding of optimum doping strategies for minimizing www.lpr-journal.org dark current densities. Self-consistent modeling of potential profile and charge variations including charged quantum dots, rather than oversimplified electrons per dot doping heuristics, is critical for deciding optimum doping in quantum dots and barriers.…”