Guibin Chen

InAs/GaAs quantum dot intermixing induced by proton implantation

We have investigated the intermixing effect of multilayer self-assembled InAs/GaAs quantum dots on photoluminescence (PL) spectra. Proton implantation combined with rapid thermal annealing is used to induce intermixing at the interface of InAs and GaAs. Intermixing results in a change of both the optical transition energy and the linewidth of the PL emission peaks. A blueshift up to 94.3 meV is obtained in the PL emission peaks. Our results show that proton implantation is an efficient method to tune the electronic states in self-assembled InAs/GaAs quantum dots.

Enhancement of room-temperature photoluminescence in InAs quantum dots

We report pronounced enhancement of room-temperature photoluminescence up to 80-fold induced by proton implantation and the rapid thermal annealing process in a multilayer InAs/GaAs quantum-dot structure. This effect is studied by a combination of material methods and resulted from both proton passivation and carrier capture enhancement effects. The maximum photoluminescence peak shift is about 23 meV, resulting from the intermixing of quantum dots. Linear dependence behavior as observed for both the nonradiative recombination time and carrier relaxation time on the ion-implantation dose. Maximum enhancement of the photoluminescence is observed for a proton implantation dose of 1.0×1014 cm−2 followed by rapid thermal annealing at 700 °C. These effects will be useful for quantum dot optoelectronic devices.

Proton-implantation-induced photoluminescence enhancement in self-assembled InAs/GaAs quantum dots

We have used proton-implantation-induced intermixing and a passivation effect to enhance the light-emission efficiency in multilayer InAs/GaAs quantum dots (QDs). Photoluminescence (PL) spectroscopy is used to study both the intermixing and passivation effects. Besides the blueshift of the luminescence peak due to the intermixing-induced energy band variation, a six times higher PL intensity increase is observed, relative to that of as-grown QDs, with a proton implantation dose of 5×1013 cm−2 followed by rapid thermal annealing at 700 °C. These effects are beneficial to both the quantum efficiency and the wavelength tuning of optoelectronic devices.

Study on optimizing the performance of infrared detectors using material chip technology

Using material chip technology, large area n-on-p planar junctions with various boron implantation doses have been fabricated on an Hg1−xCdxTe (x = 0.291) film, similarly grown using molecular beam epitaxy, for the mid-infrared wavelength range. The current–voltage characteristics of p–n junctions have been measured on a cold stage at 77 K and an optimized ion implantation dose has been discovered. Zero bias resistance of all the junctions has been calculated and shows distinct dependence upon the boron implantation doses.

Determination of Al compositional profiles across AlAs/GaAs heterostructural interface at sub-nanometer spatial resolution by thickness fringe imaging

The Al compositional profile across the AlAs/GaAs heterostructural interface before and after rapid thermal annealing was investigated by a thickness fringe-imaging technique. The diffusion of Al has been quantified by comparison between experimental thickness intensity profiles and the simulated intensity profiles

Intermixing effect on asymmetric quantum well

Ion implantation enhanced intermixing of quantum well has become an important technology in device fabrication and material modification. We report the intermixing effect in a single asymmetric coupled quantum well (GaAs/AlGaAs) at different ion implantation dose by photoluminescence. More than 80meV of blue shift of the interband transition was observed before rapid thermal annealing process. It indicates that the intermixing has almost finished during the implantation process. A diffusion length of 1nm is obtained by the theoretical analysis.