Enhancing the dot density in quantum dot infrared photodetectors via the incorporation of antimony

Abstract

The authors combine optical spectroscopic studies and infrared photodetector development to demonstrate the potential of antimony-mediated InAs quantum dot growth for the production of high performance dot-based devices. By depositing 1 ML of gallium antimonide prior to dot growth, the dot density is increased from ∼3×1010 for conventional InAs dots, to ∼6×1010cm−2. Detailed intra- and interband spectroscopic studies show no significant differences in the electron energy level configuration compared with standard InAs∕GaAs dots, while intraband absorption strength is increased. Furthermore, they have implemented this growth technique to produce a quantum dot infrared photodetector with a detectivity of ∼5×1010cmHz1∕2W−1 at 7.5μm (T=77K).

Shape control of quantum dots studied by cross-sectional scanning tunneling microscopy

“…The presence of Sb on the surface induces changes on the QD shape; the mean height is now 3.5 nm (see figure 6c) and the mean diameter 21 nm, corresponding to the dimensions of the uncapped QDs. We can explain the observed shape preservation by the well documented surfactant effect of Sb atoms [4,16]. An Sb surfactant can limit the in-plane diffusion of atoms on the surface.…”

Review of current progress in quantum dot infrared photodetectors

“…Fig. 5 shows recently published D£ values as a function of wavelength at 77-80 K. As can be seen, QDIPs [30,31,[42][43][44]47,53,57,66,103,106,[109][110][111][112][113][114][115][116][117][118][119][120][121][122][123][124] have D£ values comparable to those of QWIPs [13,92,102,[125][126][127][128][129]. This is very promising, as D£ values for QDIPs have increased by over two orders of magnitude over last 7-8 years, as seen in Fig.…”

Ga(AsSb)/GaAs/(AlGa)As heterostructures: additional hole‐confinement due to quantum islands

“…The spectra show only 1 We attribute a broad background PL at about 1.2 eV to impurities in the GaAs substrate. This interpretation is supported by the long lifetime of several tens of nanoseconds.…”

“…One approach is to grow self assembled quantum dots where material systems containing Sb have proven to be promising candidates: high dot densities [1] resulting in large peak modal gain [2] have been obtained. Problems related with the GaSb/GaAs system are the type-II alignment of the bands [2,3] and the subtle change between interfacial-misfit and Stranski-Krastanov growth-mode [4].…”