Lin Lanying

Growth and Photoluminescence of Epitaxial CeO2 Film on Si (111) Substrate

A CeO2 film with a thickness of about 80nm was deposited by a mass-analysed low-energy dual ion beam deposition technique on an Si(111) substrate. Reflection high-energy electron diffraction and x-ray diffraction measurements showed that the film is a single crystal. The tetravalent state of Ce in the film was confirmed by x-ray photoelectron spectroscopy measurements, indicating that stoichiometric CeO2 was formed. Violet/blue light emission (379.5 nm) was observed at room temperature, which may be tentatively explained by charge transitions from the 4f band to the valence band of CeO2.

Growth and properties of high purity LPE-GaAs

For LPE, a special quartz sliding boat was designed in order to avoid thermal conversion of the semi-insulating GaAs substrate during baking of the solution. Using this kind of boat, LPE-GaAs layers were grown with controlled thicknesses and smooth surfaces by a transient method. A survey on the effects of the growth conditions on the properties of epitaxial layers is given. It has been found that (1) there exists a certain incompatibility between the exclusion of oxygen and the suppression of Si and C; (2) the electrical properties of the epi-layer depend not only on the contaminating impurities in the growth solution, but also on the epitaxial growth conditions in connection with incorporating impurities and defects. After using an improved process LPE-GaAs with electrical parameters n = 1013 -1014 cm-3, μ RT = 9000 cm2/V · s,μ77K = (1.5−1.9) × 105 cm2/V · s and compensation K < 0.6 can be grown reproducibly.

LIQUID-PHASE EPITAXY GROWTH AND PROPERTIES OF GAINASSB/ALGAASSB/GASB HETEROSTRUCTURES

The GaInAsSb/AlGaAsSb/GaSb heterostructures were grown by the liquid phase epitaxy (LPE) technique. The materials were characterized by means of optical microscopy, electroprobe microanalysis (EPMA), double-crystal X-ray diffraction, capacitance-voltage (C-V) and Van der Pauw measurments, infrared absorption spectra, photoluminescence and laser Raman scattering. The results show that the materials have fine surface morphology, low lattice mismatch and good homogeneity. Room-temperature light-emitting diodes with an emission wavelength of 2.2-mu-m were obtained by using the GaInAsSb/AlGaAsSb DH structures.

Increasing the photoluminescence intensity of Ge islands by chemical etching

Self-assembled Ge islands were grown on Si(100) substrate by Si2H6-Ge molecular beam epitaxy. After being subjected to chemical etching, it is found that the photoluminescence from the etched Ge islands became more intense and shifted to the higher-energy side compared to that of the as-deposited Ge islands. This behaviour was explained by the effect of chemical etching on the morphology of the Ge islands. Our results demonstrate that chemical etching can be a way to change the luminescence property of the as-deposited islands.

Electrical properties of semi-insulating GaAs grown from the melt under microgravity conditions

A technologically important undoped semi-insulating (SI) GaAs single crystal was successfully grown in the Chinese recoverable satellite as far as we know for the first time by using a similar growth configuration described previously. The experimental results proved that the space SI GaAs crystals have a lower density of defects and defect-impurity complexes as well as a better uniformity.

Neutron irradiation induced photoluminescence from silicon crystal grown in ambient hydrogen

Abstract Photoluminescence (PL) study of neutron irradiation induced defects in float zone silicon grown in hydrogen Si[H] is reported for the first time. It is found that the thermal stability of the well-known damage lines G (0.970 eV) and I1 (1.018 eV) is significantly increased in comparison with that of crystal grown in argon. The PL lines 0.987 (HB) and 0.975 eV (HC) and their phonon replicas are observed for the samples annealed at temperatures from 350 to 600°C. The temperature dependent measurements demonstrate a transition with energy 0.978 eV (HC e ) which is caused by the thermalization on the excited states of HC transition. Both lines HB and HC are believed to arise from the isoelectronic defects associated with both hydrogen and radiation damage.

Study of Annealing Behavior and New Donor Formation in Neutron Transmutation Doped Silicon Grown in a Hydrogen Atmosphere

This paper shows that at annealing temperatures in the range (350–600°C), NTD float-zoned silicon (FZ-Si) grown in a hydrogen atmosphere and NTD grown in an argon atmosphere have very different annealing behavior. This is demonstrated by measurements of resistivity and Hall effect. The experimental results provide evidence for a new kind of donor, “hydrogen-defects” complex, in the NTD FZ-Si grown in hydrogen. The behavior of this new donor center is studied by means of electrical, optical, and DLTS measurements. After 400–450°C annealing the concentration of this donor reaches the maximum. In addition, three new hydrogen-related energy levels, (26 ± 1) meV, (37 ± 1) meV, and (265 ± 5) meV, have been observed. A shallow donor energy level (26 meV) is produced by 450°C annealing and two shallow donor energy levels (26 and 37 meV) are produced by 500°C annealing. The present experiments verify that the formation of this new donor center depends on the existence of the Si-H bond in the silicon and that these new donors are completely different from the well-known “oxygen donor” formed in CZ-Si at 450°C. These observations provide new evidence for the electrical activity of hydrogen in silicon.

Epitaxial growth of high purity GaAs in an argon atmosphere

Abstract The epitaxial growth of high purity GaAs has been carried out successfully with a leak-free and corrosion resistant AsCl 3 -Ga-Ar system. A background free carrier concentration of 7.35 × 10 12 cm -3 , a mobility of 2.05 × 10 5 cm 2 /V · s at 77 K, a peak mobility of 3.78 × 10 5 cm 2 /V · s at 35 K and a thickness of 18.0 μm were achieved by careful control of growth conditions. The effects of deposition temperature on the growth rate and mobility at 77 K were investigated in H 2 , N 2 and Ar systems respectively. It was found that the Ar system has an advantage over the N 2 system in growing high purity GaAs, especially in growing thinner epilayers. The residual impurities in high purity epilayers were investigated by IMMA and photoluminescence measurements. By these analyses one can see that the Si contamination is suppressed in the Ar system as effectively as in the N 2 system, and the dominat residual acceptor impurity of the high purity epilayer grown in the Ar system is carbon.