Abuduwayiti Aierken

Comparison of epitaxial thin layer GaN and InP passivations on InGaAs∕GaAs near-surface quantum wells

The optical properties of the in situ epitaxial GaN and InP passivated InGaAs∕GaAs near-surface quantum wells, which were fabricated by metal organic vapor phase epitaxy, are investigated. Low-temperature photoluminescence (PL), time-resolved photoluminescence, and photoreflectance are used to study the passivation effect. Both GaN and InP passivations are observed to significantly enhance the PL intensity and carrier lifetime and to reduce the surface electrical fields. Comparison of the methods shows that the epitaxial InP passivation is more effective. However, epitaxial GaN and nitridation methods are comparable with InP passivation.

Yield and leakage currents of large area lattice matched InP/InGaAs heterostructures

Demonstrating and harnessing electroluminescent cooling at technologically viable cooling powers requires the ability to routinely fabricate large area high quality light-emitting diodes (LEDs). Detailed information on the performance and yield of relevant large area devices is not available, however. Here, we report extensive information on the yield and related large area scaling of InP/InGaAs LEDs and discuss the origin of the failure mechanisms based on lock-in thermographic imaging. The studied LEDs were fabricated as mesa structures of various sizes on epistructures grown at five different facilities specialized in the growth of III-V compound semiconductors. While the smaller mesas generally showed relatively good electrical characteristics and low leakage current densities, some of them also exhibited unusually large leakage current densities. The provided information is critical for the development and design of the optical cooling technologies relying on large area devices.

Temperature dependence of droop onset in optically pumped intrinsic InGaAs/InP heterostructures

Although conventional III-V compound semiconductors are often considered not to exhibit an efficiency droop, a pronounced low temperature droop was recently measured in AlGaInP/GaAs multi-quantum well structures. In this work, we investigate the efficiency droop in simple optically pumped lattice matched InGaAs/InP single well heterostructures to exclude charge transport related effects from the measurements. The results show that droop is present in this very simplistic setup and, furthermore, starts approximately at the same carrier density as in typical III-N structures. Our results suggest that in its most fundamental form, droop can be explained by Auger-like processes.

Effect of surface states on carrier dynamics in InGaAsP/InP stressor quantum dots

The carrier dynamics in strain-induced InGaAsP/InP quantum dots (QDs) is investigated by time-resolved photoluminescence and continuous-wave photoluminescence. The stressor QDs are fabricated by depositing self-assembled InAs islands (or stressor islands) on top of a near-surface InGaAsP/InP quantum well (QW). The temporal behaviour of the QD photoluminescence transients are observed to exhibit a two-phase decay. Rate equation analyses reveal that by increasing the distance of the QW from the surface the surface capture time constant is increased considerably while the capture time constant of an electron from the QW to the QD is decreased.

Changes of photoluminescence of electron beam irradiated self-assembled InAs/GaAs quantum dots

We investigate the effects of 1.0MeV electron beam irradiation on the photoluminescence of self-assembled InAs/GaAs quantum dots. After irradiation doses up to 1×1016e-/cm2 , photoluminescence of all samples was degraded dramatically and some additional radiation-induced changes in photo-carrier recombination from QDs, which include a slight increase in PL emission with low electron doses under different photo-injection condition in two samples, are also noticed. Different energy shift was observed in two samples with different Quantum Dot sizes. We attribute this remarkable phenomenon to combination of stress relaxation induced red-shift and In-Ga intermixing caused blue-shift.

Changes in output parameters of 1 MeV electron irradiated upright metamorphic GaInP/GaInAs/Ge triple junction solar cell

The changes in output parameters of 1 MeV electron irradiated MOCVD grown upright metamorphic (UMM) GaInP/GaInAs/Ge triple junction solar cells have been studied. Non-ionizing energy loss (NIEL) approach and MULASSIS simulation were applied for analyzing the effects of irradiation induced displacement damage on cell performance. The influence of base thickness on radiation resistance has been studied by changing the base thickness of top GaInP and middle GaInAs subcell, respectively. The experimental results show that the electrical parameters, Voc, Isc, and Pmax of UMM cell degrade with the increase of electron fluence. The change of spectra response indicates middle GaInAs subcell degrades more severe than top GaInP subcells, and the base thickness of two subcells has different effects on spectra response of UMM cell.

1-MeV electron irradiation effects on InGaAsP/InGaAs double-junction solar cell and its component subcells

Key Laboratory of Functional Materials and Device for Special Environments, Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, Urumqi 830011, China; Xinjiang Key Laboratory of Electronic Information Material and Device, Urumqi 830011, China; University of Chinese Academy of Sciences, Beijing 100000, China; Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Suzhou 215123, China

Enhanced 1.3 µm luminescence from InGaAs self-assembled quantum dots with a GaAsN strain-compensating layer

We have studied room temperature (RT) photoluminescence (PL) emission and strain characteristics of InGaAs quantum dots (QDs) grown on GaAs using metal organic vapor phase epitaxy. The InGaAs QDs were covered by a 10 nm thick GaAsN layer having a nitrogen composition of either 0.3% or 0.9% and a following 50 nm thick GaAs layer. The RT-PL emission intensity of InGaAs QDs has been increased with reduced linewidth for 1.3 µm device application by using GaAsN strain-compensating layers. The Raman spectra of InGaAs QDs covered by GaAsN0.009 show the InGaAs QD phonon frequency shift toward that of InGaAs surface QDs, which gives clear evidence for strain compensation.