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We describe the evolution of optical power, threshold current, and emission wavelength of a lattice-matched InGaAs/InAlAs Quantum-Cascade Laser (QCL) emitting at 13 μm grown by gas-source molecular-beam epitaxy under thermal annealing. Pieces from the same 2-in wafer were annealed at 600 °C, 650 °C, or 700 °C for 1 h; one control piece remained unannealed. No change in threshold current and emission wavelength was observed. The slope efficiency and maximum emission power increase for the 600 °C anneal, but higher annealing temperatures resulted in degraded performance. This result stands in contrast with the observation that strain-compensated structures cannot withstand annealing temperature of 600 °C. Useful information for post-growth processing steps and the role of interface roughness in QCL performance are obtained. [ABSTRACT FROM AUTHOR]

Zn 1- x Mg x Se y Te 1- y layers have been grown on (100) ZnTe substrates by low-pressure metalorganic vapor phase epitaxy using dimethylzinc, bis-methylcyclopentadienyl magnesium ((MeCp) 2 Mg), diethylselenide and diethyltelluride as source materials. The Mg mole fraction of Zn 1- x Mg x Se y Te 1- y layer can be controlled successfully by varying (MeCp) 2 Mg transport rate. P -type doping of this material has been tried using tris-dimethylaminophosphorus as a dopant source. The influence of annealing temperature or dopant transport rate upon the electrical property has been investigated. All the layers show p -type conduction even without annealing. Through this study, a maximum carrier concentration of 2.5×10 18 cm −3 is obtained. [ABSTRACT FROM AUTHOR]

Photoluminescence (PL) spectra and electrical properties of both as-grown and annealed phosphorus-doped ZnTe layers grown by low-pressure metalorganic vapor phase epitaxy have been clarified as a function of reactor pressure or dopant transport rate. The carrier concentration of as-grown layer increases with decreasing reactor pressure or increasing dopant transport rate, in good agreement with PL behavior. Similar tendency is also found for annealed layer. Annealing treatment induces the enhancement of the carrier concentration, independent of reactor pressure or dopant transport rate. Through this study, a high carrier concentration near 10 19 cm −3 has been attainable. [ABSTRACT FROM AUTHOR]

The N–H related defects at 3124 cm -1 are found to be acceptors in GaAsN grown by chemical beam epitaxy (CBE), by comparing the concentrations of N–H defects with those of acceptors as a function of annealing condition. The vibrations of N–H defects appear as local vibration modes at 2952, 3011, 3098, and 3124 cm -1 using Fourier transform infrared (FTIR) spectroscopy. The integrated absorptions at 2952 and 3098 cm -1 decrease, at 3011 cm -1 remain small, while at 3124 cm -1 increases due to the annealing treatment. On the other hand, the concentration of acceptors increases with the annealing time, based on capacitance–temperature (C–T) measurement. The densities of N–H defects at 3124 cm -1 and those of acceptors are almost equal independent of the annealing condition. This result suggests that the N–H defects appearing at 3124 cm -1 play the role of acceptors in GaAsN grown through CBE. [ABSTRACT FROM AUTHOR]

Rapid thermal annealing (RTA) has been performed on InGaAsP solar cells with the bandgap energy of 1 eV grown by molecular beam epitaxy. With the employment of RTA under an optimized condition, the open voltage was increased from 0.45 to 0.5 V and the photoelectric conversion efficiency was increased from 11.87–13.2%, respectively, which was attributed to the crystal quality improvement of p-type InGaAsP and therefore a reduced recombination current inside depletion region. The integral photoluminescence (PL) intensity of p-type InGaAsP increased to 166 times after annealing at 800 °C and its PL decay time increased by one order of magnitude. While the changes of nominally undoped and n-doped InGaAsP were negligible. The different behaviors of the effect of RTA on InGaAsP of different doping types were attributed to the highly mobile “activator” – beryllium (Be) atom in p-type InGaAsP. [ABSTRACT FROM AUTHOR]

GaAs 1− x Bi x /GaAs multiple quantum well heterostructures were grown by organo-metallic vapor phase epitaxy (OMVPE) at low temperatures and were subsequently in-situ annealed under an arsine (AsH 3 ) overpressure in the OMVPE reactor. Photoluminescence (PL) measurements were performed to establish the optimized annealing condition for the highest luminescence intensity, as well as high resolution X-ray diffraction (XRD) measurements to detect any structural changes after annealing. In addition, the complex compositional profile and the interfacial abruptness were deduced from the combined XRD analysis with the transmission electron microscopy. A 5-fold increase in the PL intensity at room temperature was observed after annealing under the optimized conditions. Using the optimized annealing conditions, single junction solar cells (SJSC) incorporating 5-period GaAs 0.964 Bi 0.036 /GaAs (32 nm/20 nm) heterostructures for the device base region were fabricated and characterized. The spectral dependence of the external quantum efficiency of the SJSC exhibited improved spectral response as a result of the optimized in-situ annealing, with extended absorption edge up to 1.07 eV. [ABSTRACT FROM AUTHOR]

In this paper, detector-grade CdMnTe:In (CMT:In) single crystals were annealed under Te atmosphere with various annealing times. The results indicated that the density of Te inclusions had not changed as the annealing time increased, whereas the resistivity exhibited an initial increase followed by a decrease. The conduction type was changed from weak n -type conduction in as-grown crystal to p -type conduction in 60 h annealed crystal. The IR transmittance decreased obviously as the annealing time increased. In the PL spectra, the obvious reduction of the intensity of ( D °, X ) peak and the increase of the intensity of the D complex peak in the annealed CMT:In crystals indicated a degradation of the crystal quality. The energy resolution of the detector fabricated with 15 h annealed crystal was improved, whereas the μτ values of the detectors fabricated with all annealed crystals were reduced. Specially, the characteristic peak of 241 Am γ-ray could not be observed in the detectors fabricated by 60 h annealed crystals. Therefore, optimal annealing temperature and the duration are 773 K and 15 h, respectively. [ABSTRACT FROM AUTHOR]

CuInS2 (CIS) thin films were prepared by sulfurization of In/Cu stacked precursor films. Prior to sulfurization the stacked metallic precursors were subjected to the soft annealing in Ar atmosphere at different time (10, 30, and 60min) and temperature (100°C and 300°C). The effect of soft annealing condition on the structural, morphological and optical properties of CIS films was investigated. X-ray diffraction, Raman, and X-ray photoelectron spectroscopy studies showed that the sulfurized thin films exhibited a CIS tetragonal structure with minor secondary phases such as Cu2−x S and CuIn5S8. The secondary phases were minimized by introducing soft annealed process in the CIS thin films. Void free CIS microstructures have been observed for soft annealed CIS films. The band gap energy of CIS films were increased from 1.37 to 1.5eV depending on the soft annealing conditions. [ABSTRACT FROM AUTHOR]

Abstract: A crack-free CdGeAs2 single crystal 15mm in diameter and 50mm in length was grown in a three-zone tubular furnace by the modified vertical Bridgman method. During the annealing processes, the effects of treatments with different atmosphere, different temperatures and time were investigated. The as-grown and annealed wafers were characterized using X-ray diffractometer (XRD), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and IR microscope. Conclusively, the results confirm annealing could improve the optical qualities of as-grown CdGeAs2 crystal. The best result was obtained under cover-up with CdGeAs2 polycrystalline powder at 450°C for 150h and the IR transmittance of the wafer measured by FTIR was up to 48.65% nearby 5.5μm and exceeded 50% in the range of 8–12μm. Additionally, the monolithic homogeneity of the crystal has also been greatly improved after annealing under cover-up with polycrystalline powder. [Copyright &y& Elsevier]

Abstract: We report the behavior of nitrogen implanted into GaAs wafer upon annealing in the range of 500°C to 1000°C. The SIMS results show out-diffusion of nitrogen and the peaks in the distribution profiles of implanted nitrogen broadening. XPS measurements indicate that the N bonding configuration before annealing is contributed by NAs, interstitial NN and the NAs complex. However, NAs complex disappears completely upon annealing at temperature higher than 700°C. The spectra and quantitative analysis reveal that a saturation of NAs happens as annealing temperature increases. Before the saturation, the substitional NAs keeps rising, which leads to the elevation of n-type doping level in host. Whereas beyond the saturation, the excess thermal energy beyond saturation triggers the kick-out mechanism and induces dramatic increase in the amount of NN split interstitials, resulting in suppression of the nitrogen out-diffusion during annealing and pining of the Fermi level. [Copyright &y& Elsevier]

Abstract: Boule of GaN crystal was grown with 50mm diameter and 3mm thickness by hydride vapor phase epitaxy and cut using a wire saw to produce freestanding wafers. These were, mechanically polished with diamond slurry and followed with chemical mechanical polishing for final surface preparation. Surface morphology was examined by non-contact mode atomic force microscopy before and after thermal annealing process performed at 700, 800, 900, and 1000°C for 1h, in air. Wafers with optimum surface quality submitted to thermal annealing treatment at 900°C were characterized by reduced scratched density and residual stress, and surface roughness of 0.096nm. Surface quality improvement was confirmed by relatively large recovery of the room temperature near band edge luminescence intensity. [Copyright &y& Elsevier]

Abstract: ZnSe ceramic material doped with Te was produced at room temperature via compaction of nanocrystalline powders. Phase composition and microstructure were investigated and the effect of compression and heat treatment on phase transformations and grain growth was studied. Two ways of transition from metastable hexagonal to stable cubic phase were found. Two-staged annealing at Т=700°С, 2h followed by annealing at Т=800°С, 2h brings to complete transformation from wutzite to sphalerite phase. However, under these conditions some additive is lost during the heat treatment. Annealing of the compacted material at Т=800°С, 2h, its slow cooling to room temperature causes transformation into two sphalerite lattices with the unit cell parameters a 1=5.660Å and a 2=5.686Å, which transform during holding at room temperature into one sphalerite lattice with a ZnSe(Te)=5.681±0.003Å. This heat treatment provides formation of the stable cubic state of the solid solution containing 2.5wt% Te in ZnSe(1−x)Te x . [Copyright &y& Elsevier]

Abstract: We have investigated the annealing effect of V-doped GaN (GaN:V) epitaxial layers grown on sapphire by metal organic chemical vapor deposition (MOCVD). The film was annealed at a temperature of 1075°C for 30min in N2 ambient after growth. The structural, surface morphology and optical properties of GaN:V films were studied by high resolution X-ray diffraction (HRXRD), atomic force microscope (AFM) and photoluminescence (PL). The results show that the annealing makes for the destruction in the crystal quality and surface morphology. After thermal annealing, the photoluminescence (PL) measurement showed a reduction of the blue luminescence (BL) band observed in GaN:V at room temperature (RT). The phenomenon is attributed to vanadium diffusion or to the V-related complex dissociation. Near-band-edge (NBE) peak exhibited a red shift after 1075°C anneal. This is due to the decrease in the level of strain. In the infrared region, we observed the emergence of the line 0.93eV accompanied by a decrease in the intensity of the 0.82eV emission. Their possible origins are discussed. [Copyright &y& Elsevier]

Abstract: In this paper, we report the growth of M -plane GaN thin films on LiGaO2 (100) substrates pre-annealed in vacuum and in air ambient. The surface of M -plane GaN film grown on the LiGaO2 (100) substrate pre-annealed in air ambient was significantly improved. X-ray diffraction data showed that the M -plane GaN thin film grown on the LiGaO2 (100) substrate pre-annealed in air ambient has better crystal quality than that grown on the LiGaO2 (100) substrate pre-annealed in vacuum. In addition, the strain generated between GaN thin film and LiGaO2 substrate was relaxed when the GaN thin film grew on the LiGaO2 substrate pre-annealed in air ambient. It revealed that the thermal annealing LiGaO2 substrate in air ambient can suppress the formation of lithium-rich surface effectively, and then one can grow a high quality M -plane GaN thin film on the LiGaO2 substrate. [Copyright &y& Elsevier]