Intraband and interband photocurrent spectroscopy and induced dipole moments of InAs/GaAs(001) quantum dots in n–i–n photodetector structures

Abstract

Intraband-transition-induced dipoles in self-assembled InAs/GaAs(001) quantum dots Appl.

Intraband-transition-induced dipoles in self-assembled InAs/GaAs(001) quantum dots

“…The capped QDs are likely to have an effective height and base not the same as the uncapped islands but given our very low temperature (Ͻ350°C) capping such differences are minimized compared to conventional cap layer growth at ϳ500°C. In the n-i-n structures used here, the electron ground states of the QDs are only partially occupied 11 by electrons contributed and/or injected from the heavily doped contact layers. All photocurrent ͑photovoltage͒ spectra were recorded on 250 m diameter mesas ͑with bottom contract grounded͒ under normal-incidence geometry using a current ͑voltage͒ preamplifier and a rapid-scan Fourier-transform infrared ͑FTIR͒ spectrometer.…”

InAs quantum dot infrared photodetectors with In0.15Ga0.85As strain-relief cap layers

“…The InAs QDIP studied in this work belongs to the class of n-i-n structure QDIPs under examination by us. [5][6][7][8][9][10][13][14][15] Figure 1͑a͒ shows a schematic of the QDIP structure. The sample was grown on semi-insulating GaAs ͑001͒ substrates by solid-source molecular beam epitaxy.…”

“…As a potential candidate for mid-infrared ͑3-5 m͒ and far-infrared ͑8-14 m͒ photon detection, the quantum dot infrared photodetector ͑QDIP͒ has been the subject of extensive research efforts in recent years. Normal-incidence QDIPs with n-n-n [1][2][3][4] and n-i-n [5][6][7][8][9][10] vertical configurations have been reported. Compared with quantum well infrared photodetectors, QDIPs are sensitive to normal-incidence infrared radiation owing to three-dimensional confinement of the electrons in the quantum dots, a characteristic that is advantageous for focal plane arrays.…”

Origin of photocurrent in lateral quantum dots-in-a-well infrared photodetectors

“…[9][10][11][12] For InAs/ GaAs QDs, extensive experimental and theoretical studies have been made to map the electronic structure and their possible intersubband transitions. [13][14][15] Despite these prevailing studies, the identifications of the intersubband transitions responsible for the absorption and the photocurrent ͑PC͒ diverge in the literature. For InAs/ InGaAs DWELL structures the identifications of the intersubband transitions are even less certain, although attempts have been made by some groups.…”