Influence of thermal annealing on the electron emission of InAs quantum dots containing a misfit defect state

Abstract

We have investigated the effect of postgrowth thermal annealing on the electron emission from InAs quantum dots ͑QDs͒ containing a misfit-related defect state induced by strain relaxation. Additional carrier depletion in the GaAs bottom layer near the QD, caused by the defect state, can effectively suppress electron tunneling from the QD, leading to the observation of a thermal emission from the QD electron ground state to the GaAs conduction band with a large emission energy of 213 meV, in contrast to defect-free nonrelaxed QDs in which an emission of 58 meV from the QD electron ground state to first excited state is observed. The emission energy is reduced to 193 meV and to 164 meV after annealing at 650 and 700°C for 1 min, respectively. This emission energy reduction is correlated with the photoluminescence blueshift which is attributed to the interdiffusion of atoms across the QD interface. The electron emission from the QD first excited and ground states is found to be a thermal emission at high temperatures and a tunneling emission at low temperatures. The tunneling energy barrier is found to be comparable to the thermal emission energy, supporting a thermal emission to the GaAs conduction band. This study illustrates a significant effect of a defect state on the electron-emission process in the QDs, suggesting the possibility of modifying the electron emission time of the QDs by purposely introducing a deep defect state.

Two-Color Single-Photon Emission from InAs Quantum Dots: Toward Logic Information Management Using Quantum Light

“…This asymmetrical X 0 −X −1 cross correlation shape has been previously reported as a consequence of the different regeneration times for X 0 and X −1 exciton species and is modeled by assuming a dynamic capture time. 66−68 In our model, we consider that carrier escape out of the QD takes place either via deep levels or interface defects 37,69,70 whose characteristic times are included in the total regeneration time of the excitonic complex.…”

“…It is important to remember that the best-fit parameters described above serve to reproduce the asymmetrical pattern found in the X 0 –X –1 cross correlation HBT experiment, as clearly observed in Figures d (excitation at 790 nm) and b (two-color laser excitation). This asymmetrical X 0 –X –1 cross correlation shape has been previously reported as a consequence of the different regeneration times for X 0 and X –1 exciton species and is modeled by assuming a dynamic capture time. − In our model, we consider that carrier escape out of the QD takes place either via deep levels or interface defects ,, whose characteristic times are included in the total regeneration time of the excitonic complex.…”

Small signal modulation characteristics of quantum dot lasers and the effect of annealing and doping

“…Furthermore, the p-doped sample exhibited a higher thermal energy onset for the occurrence of significant intermixing, which is due to the presence and diffusion of Be atoms in the p-doped structure [61]. In addition, experimental evidences have shown that intermixing can greatly reduce the inhomogeneous broadening by producing better dot uniformity [28][29][30][31].…”