Resonant Raman Scattering and Photoluminescence Emissions from Above Bandgap Levels in Dilute GaAsN Alloy

The transitions of E0 ,E0 ＋A0, and E＋ in dilute GaAs（1-x） Nx alloys with x = 0.10% ,0.22% ,0.36% ,and 0.62% are observed by micro-photoluminescence. Resonant Raman scattering results further confirm that they are from the intrinsic emissions in the studied dilute GaAsN alloys rather than some localized exciton emissions in the GaAsN alloys. The results show that the nitrogen-induced E E＋ and E0 ＋ A0 transitions in GaAsN alloys intersect at a nitrogen content of about 0.16%. It is demonstrated that a small amount of isoelectronic doping combined with micro-photoluminescence allows direct observation of above band gap transitions that are not usually accessible in photoluminescence.

低能离子束方法制备磁性Fe-Si合金薄膜

利用质量分离的低能离子束技术,获得了磁性Fe-Si合金薄膜.利用俄歇电子能谱法(AES)、X射线衍射法(XRD)以及交变梯度样品磁强计(AGM)测试了样品的组分、结构以及磁特性.测试结果表明在室温下制备的Fe-Si合金是Fe组分渐变的非晶薄膜,具有室温铁磁性.当衬底温度为300℃时制备的非晶Fe-Si薄膜中有Fe硅化物FeSi相产生,样品的铁磁性被抑制.

低能离子束方法制备重掺杂Fe的Si:Fe固溶体

利用质量分离的低能离子束方法,以离子能量为1000eV,剂量为3×1017cm-2,室温下往p型Si(111)单晶衬底注入Fe离子,注入的样品在400 C真空下进行热处理.俄歇电子能谱法(AES)对原位注入样品深度分析表明Fe离子浅注入到p型Si单晶衬底,注入深度约为42nm.X射线衍射法(XRD)对热处理样品结构分析发现只有Si衬底的衍射峰,没有其他新相.X射线光电子能谱法(XPS)对热处理样品表面分析发现Fe2p束缚能对应于单质Fe的峰,没有形成Fe的硅化物.这些结果表明重掺杂Fe的Si:Fe固溶体被制备.电化学C-V法测量了热处理后样品载流子浓度随深度的分布,发现Fe重掺杂Si致使Si的导电类型从p型转为n型,Si:Fe固溶体和Si衬底形成pn结,具有整流特性.

低能离子束方法制备Fe组分渐变的Fe-Si薄膜

利用质量分离的低能离子束技术，获得了Fe组分渐变的Fe-Si薄膜。利用俄歇电子能谱法(AEs)、x射线衍射法(XRD)以及x射线光电子能谱法(XPS)测试了薄膜的组分、结构特性。测试结果表明，在室温下制备的Fe-Si薄膜呈非晶态。非晶薄膜在400℃下退火20 rmn后晶化，没有Fe的硅化物相形成。退火后Fe-Si薄膜的Fe组分从表面向内部逐渐降低。

Influence of Fe Doping Concentration on Some Properties of Semi-Insulating InP

Properties of Fe-doped semi-insulating (SI) InP with different iron concentrations are studied by using Hall effect, current-voltage (I-V), photoluminescence spectroscopy (PL) and photocurrent spectroscopy (PC) measurements. I-V characteristics of SI InP strongly depend on Fe doping concentration. Fe doping concentration also influences optical properties and defective formation in as-grown SI InP. Band-gap narrowing phenomenon and defects in Fe doped SI InP are studied using PI and PC.

Metalorganic Chemical Vapor Deposition of GaNAs Alloy Using Dimethylhydrazine as Nitrogen Precursor

GaNAs alloy is grown by metalorganic chemical vapor deposition (MOCVD) using dimethylhydrazine (DMHy) as the nitrogen precursor. High-resolution X-ray diffraction (HRXRD) and secondary ion mass spectrometry (SIMS) are combined in determining the nitrogen contents in the samples. Room temperature photoluminescence (RTPL) measurement is also used in characterizing. The influence of different Ga precursors on GaNAs quality is investigated. Samples grown with triethylgallium (TEGa) have better qualities and less impurity contamination than those with trimethylgallium (TMGa). Nitrogen content of 5.688% is achieved with TEGa. The peak wavelength in RTPL measurement is measured to be 1278.5nm.

Investigation of Residual Donor Defects in Undoped and Fe-Doped LEC InP

The free electron concentration of as-grown liquid encapsulated Czochralski (LEC) InP measured by Hall effect is much higher than the concentration of net donor impurity determined by glow discharge mass spectroscopy. Evidence of the existence of a native donor hydrogen-indium vacancy complex in LEC undoped and Fe-doped InP materials can be observed with infrared absorption spectra. The concentration increase of the donor complex correlates with the increase of ionized deep acceptor iron impurity Fe~(2+) concentration in Fe-doped semi-insulating (SI) InP. These results indicate that the hydrogen-indium vacancy complex is an important donor defect in as-grown LEC InP, and that it has significant influence on the compensation in Fe-doped SI InP.

Characterization of Ga N_x As_(1 - x) Alloy Grownon Ga As by Molecular Beam Epitaxy

集成光电子学国家重点实验室基金,国家863计划,国家自然科学基金,中科院项目

硅双极晶体管的低温h_（FE）

低温下h_(FE)主要决定于发射效率γ和集电区倍增因子M。影响γ的是禁带收缩和基区费米能级。M则主要由中性杂质被碰撞电离而造成的电流倍增效应决定，并且这是一种自抑制效应。以上观点与实验结果基本相符合。

硅中Rh-B络合物性质的理论研究

于2010-11-23批量导入

氧合血红蛋白Fe-O2键合态ab initio研究

于2010-11-23批量导入

Effect of rapid thermal annealing on the Raman spectrum of Si0.33Ge0.67/Si (100) alloy

The effect of thermal annealing on the Raman spectrum of Si0.33Ge0.67 alloy grown on Si (100) by molecular beam epitaxy is investigated in the temperature range of 550-800 degrees C. For annealing below 700 degrees C, interdiffusion at the interface is negligible and the residual strain plays the dominant role in the Raman shift. The strain-shift coefficients for Si-Ge and Ge-Ge phonon modes are determined to be 915 +/- 215 cm(-1) and 732 +/- 117 cm(-1), respectively. For higher temperature annealing, interdiffusion is significant and strongly affects the Raman shift and the spectral shape.

Pressure behavior of Te isoelectronic centers in S-rich ZnS1-xTex alloy

The photoluminescence from ZnS1-xTex alloy with 0 < x < 0.3 was investigated under hydrostatic pressure up to 7 GPa. Two peaks were observed in the alloys with x < 0.01, which are related to excitons bound to isolated Te isoelectronic impurities (Te-1 centers) and Te pairs (Te-2 centers), respectively. Only the Te-2 related emissions were observed in the alloys with 0.01 < x < 0.03. The emissions in the alloys with 0.03 < x < 0.3 are attributed to the excitons bound to the Te-n (n greater than or equal to 3) cluster centers. The pressure coefficient of the Te-1 related peak is 89(4) meV/GPa, about 40% larger than that of the band gap of ZnS. On the other hand, the pressure coefficient of the Te-2 related emissions is only 52(4) meV/GPa, about 15% smaller than that of the ZnS band gap. A simple Koster-Slater model has been used to explain the different pressure behavior of the Te-1 and Te-2 centers. The pressure coefficient of the Te-3 centers is 62(2) meV/GPa. Then the pressure coefficients of the Te-n centers decrease rapidly with further increasing Te composition.

Fe-57 Mossbauer spectroscopic and magnetic studies of R3Fe29-xVx (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy)

Mossbauer spectra for Fe atoms in the series of R3Fe29-xVx (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy) compounds were collected at 4.2 K. The ratio of 14.5 T/mu(B) between the average hyperfine field B-hf and the average Fe magnetic moment mu(Fe)(MS), obtained from our data, in Y3Fe29-xVx is in agreement with that deduced from the RxTy alloys by Gubbens et al. The average Fe magnetic moments mu(Fe)(MS) in these compounds at 4.2 K, deduced from our Mossbauer spectroscopic studies, are in accord with the results of magnetization measurement. The average hyperfine field of the Fe sites for R3Fe29-xVx at 4.2 K increases with increasing values of the rare earth effective spin (g(J) - 1) J, which indicates that there exists a transferred spin polarization induced by the neighboring rare earth atom.

Mossbauer spectroscopy study of Fe-57 in R3Fe29-xTx (R=Y, Ce, Nd, Sm, Gd, Tb and Dy; T=V and Cr)

Fe-57 Mossbauer spectra for the Fe atoms in the R3Fe29-xTx (R=Y, Ce, Nd, Sm, Gd, Tb, Dy; T=V, Cr) compounds were collected at 4.2 K. The analysis of Mossbauer spectra was based on the results of magnetization and neutron powder diffraction measurements. The average Fe magnetic moments at 4.2 K, deduced from our data, are in accord with magnetization measurements. The average hyperfine field of Tb3Fe29-xCrx (x=1.0, 1.5, 2.0, and 3.0) decreases with increasing Cr concentration, which is also in accordance with the variation of the average Fe magnetic moment in the Tb3Fe29-xCrx compounds.