Abstract
We propose a tunnel-injection structure, in which WS2 quantum dots (QDs) act as the injector and InGaN/GaN quantum wells (QWs) act as the light emitters. Such a structure with different barrier thicknesses has been characterized using steady-state and time-resolved photoluminescence (PL). A simultaneous enhancement of the PL intensity and PL decay time for the InGaN QW were observed after transfer of charge carriers from the WS2-QD injector to the InGaN-QW emitter. The tunneling time has been extracted from the time-resolved PL, which increases as the barrier thickness is increased. The dependence of the tunneling time on the barrier thickness is in good agreement with the prediction of the semiclassical Wentzel–Kramers–Brillouin model, confirming the mechanism of the tunnel injection between WS2 QDs and InGaN QWs.
Highlights
Development of semiconductor heterostructures for applications in devices such as light-emitting diodes (LEDs), phototransistors, and photovoltaics is of great interest in research today.[1,2] One of the recent interests in semiconductor heterostructures is the incorporation of two-dimensional materials with conventional semiconductors.[3,4] Carrier or energy transfer between two-dimensional materials and semiconductors was proven to be promising for the enhancement of electrical and optical properties of the semiconductor heterostructures
This average size is comparable with the result of Ghorai et al, where the size of their WS2 quantum dots (QDs) produced by prolonged sonication is around 3.5 nm.[15]
From the above data (Fig. 3, 5 and 6) we suggest that the enhanced PL intensity and PL decay time in the InGaN quantum wells (QWs) are attributed to the transfer of the photogenerated carriers from
Summary
Development of semiconductor heterostructures for applications in devices such as light-emitting diodes (LEDs), phototransistors, and photovoltaics is of great interest in research today.[1,2] One of the recent interests in semiconductor heterostructures is the incorporation of two-dimensional materials with conventional semiconductors.[3,4] Carrier or energy transfer between two-dimensional materials and semiconductors was proven to be promising for the enhancement of electrical and optical properties of the semiconductor heterostructures. We propose that the WS2 QDs can be an efficient injector in the tunnel-injection structure because two-dimensional materials have less dangling bonds on their surfaces or interfaces. This is advantageous for the tunnel injection structure since a high-quality interface produces an efficient carrier transfer between the injector and the light emitter. We investigated the tunnel injection from WS2 QDs to InGaN/GaN quantum wells (QWs) for developing the active region in the light emitting devices. The spatial separation between the injector (WS2 QDs) and the light emitter (InGaN QWs) was controlled by a potential barrier layer (GaN), where the barrier layer has different thicknesses ranging from 2 to 8 nm. The steady-state and time-resolved photoluminescence (PL) of the InGaN QW as a function of the barrier thickness were investigated and analyzed by the Wentzel–Kramers–Brillouin (WKB) approximation
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