High quantum efficiency dots-in-a-well quantum dot infrared photodetectors with AlGaAs confinement enhancing layer

Abstract

We demonstrate the high quantum efficiency InAs∕In0.15Ga0.85As dots-in-a-well (DWELL) quantum dot infrared photodetectors (QDIPs). A thin Al0.3Ga0.7As layer was inserted on top of the InAs quantum dots (QDs) to enhance the confinement of QD states in the DWELL structure. The better confinement of the electronic states increases the oscillation strength of the infrared absorption. The higher excited state energy also improves the escape probability of the photoelectrons. Compared with the conventional DWELL QDIPs, the quantum efficiency increases more than 20 times and the detectivity is about an order of magnitude higher at 77K.

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.…”

“…Various groups have been working on methods to improve the structural and optical properties of quantum dots [31,[33][34][35][36][37][38][39][40] to increase carrier lifetime as well as to increase quantum dot density. Dark current levels have been significantly reduced by using AlGaAs as current blocking layers [41][42][43].…”

Detection wavelength and device performance tuning of InAs QDIPs with thin AlGaAs layers

“…Recently, we also demonstrated high quantum efficiency QDIPs with the insertion of thin high bandgap barriers on top of QDs in the DWELL structure [10]. In QDs, due to the smaller size and the intermixing with the barriers, the wavefunctions of the excited states extend further out of the QDs [11].…”

“…Thus, quantum dot infrared photodetectors (QDIPs) are of great potential to overcome the drawbacks of the commercialized QWIPs and become low cost, high temperature operation infrared detectors [1][2][3][4][5][6][7][8][9][10]. From the early stage of the QDIPs study, it is well known that the performance of QDIPs is quite limited with the simple InAs/GaAs QD structure.…”

Complementary split-ring resonator antenna coupled quantum dot infrared photodetector

“…25, taking into account the thermal noise and the dark and BG contributions to the shot noise, 43,44 we estimated The relatively low values of R and D * are inherently related to the detector structure based on a single layer of QDs, which has a significantly lower efficiency with respect to multi-layer QDIPs, for which responsivity values more than five orders of magnitude higher are reached. [45][46][47] A significant increase of the quantum efficiency can be achieved by including an extraction layer, enhancing the escape of the photoexcited electrons from the QDs. In Ref.…”