摘要:

Hydrogenated amorphous silicon films have been grown by radio frequency (rf) plasma chemical vapor deposition with the addition of small amounts (up to 20%) of dichlorosilane to the silane. Results show that as the amount of dichlorosilane is increased, the films are more resilient to the creation of light induced defects. Under intense pulsed laser illumination (5 mJ/pulse, 10 ns, 10 Hz) the steady state defect density measured by the constant photocurrent method (CPM) is reduced by over one order of magnitude to 4×1016cm−3as compared to ∼5×1017cm−3for films grown under identical conditions with pure silane. Furthermore, there is a threefold increase in the deposition rate over the range of mixture ratios studied here. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113612

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A new type of hydrogenated nanocrystalline Si film with high electronic conductivity is investigated by means of transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). Nearly parallel columnar structures with growth orientation along the [110] zone axis of Si are found from cross‐sectional TEM images of the film. HRTEM observation reveals that these columns are composed of nanocrystallites (3–6 nm size) and dendritelike growth morphology, while in the region between columns the texture consists of smaller sized (<3 nm) grains embedded in a hydrogenated amorphous Si. The volume fraction of the crystalline component is about 58% measured by Raman spectroscopy. The conductivity of the film is very high, about 10−1(&OHgr; cm)−1. It is considered that this is directly related to the characteristic structure of the film. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113613

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

In this work we investigate the diffusion of silicon interstitials in bulk silicon and silicon‐on‐insulator structures. The interstitials that are injected by an oxidation process are monitored by the growth of oxidation stacking faults. The silicon‐on‐insulator structures are obtained by the silicon wafer bonding technique that gives us the advantage of monitoring both the lateral and the vertical distribution of point defects by special pretreatment of the bonded wafers. We observe a decrease in the lateral diffusion of interstitials as the thickness of silicon decreases. Simulation of these results reveals fundamental properties of point defects. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113815

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

An experimental technique involving the measurement of thermally stimulated exoelectron emission has been shown to be capable to detecting the surface states, caused by the presence of metal impurities, at the surface of silicon. The ionization energies of the surface states induced by the thermal diffusion of silver, gold, copper, and aluminum in silicon are estimated from this technique. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113816

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Ultrathin oxide patterns of a linewidth of 50 A˚ have been created on Si(100)‐2×1 surfaces by a scanning tunneling microscope operating in ultrahigh vacuum. The oxide thickness is estimated to be 4–10 A˚. The morphology and spectroscopy of the oxide region are obtained. Hydrogen passivation is used as an oxidation mask. The defects caused by oxidation in the passivated region before and after the hydrogen desorption are compared and discussed. The multistep silicon processings by an ultrahigh vacuum scanning tunneling micropscope is thus demonstrated. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113817

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The potential of the heated implant technique was investigated for ⟨100⟩ germanium silicon layers. Germanium silicon layers with increasing germanium peak concentrations (1% to 16%) were implanted at different energies (40 keV, 60 keV), dose rates (1 &mgr;A/cm2, 0.1&mgr; A/cm2) and at different substrate temperatures (24 °C, 300 °C, 380 °C). The layers were subsequently annealed for 10 minutes at 1010 °C. The final crystalline quality of the annealed layers was investigated by 300 keV alpha and 150 keV proton channeling spectrometry. For room temperature implants, regrown layers with peak concentrations up to 6.5% showed good crystalline quality while the high concentration layers (16% peak concentration) showed significant residual damage. The final quality of the heated implants was consistently and substantially lower than that of the room temperature implants. Varying the implant temperature, dose rate and energy did not produce significant improvements nor did a modification of the annealing schedule. The fact that the room temperature implants produced consistently better final quality layers than the heated implants for ⟨100⟩ layers is in contrast with results obtained previously for ⟨111⟩ layers. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113818

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Second harmonic generation (SHG) at 1.064 &mgr;m reflected by thin films (20–60 nm) of layered GaSe epitaxially grown on Si(111) substrates is reported. Comparison with a theoretical calculation, taking into account all interfering waves, is made as a function of growth temperature, evidencing a large discrepancy at lower growth temperature. This discrepancy is attributed to the existence of antiphase domains whose nonlinear polarizations are opposite. Reflected SHG thus allows to probe the existence of an orientational disorder undetectable with electron or x‐ray diffraction techniques. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113819

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The interband transitions in single‐crystal GaN films grown by metalorganic chemical vapor deposition (MOCVD) have been studied as a function of temperature (15≤T≤300 K) by reflectance and photoluminescence measurements. At low temperatures, well‐resolved spectral features corresponding to the GaN band structure were observed. The energies of the excitonic interband &Ggr;V9−&Ggr;C7,&Ggr;V7(upper band)−&Ggr;C7and &Ggr;V7(lower band)−&Ggr;C7transitions are found to be 3.485, 3.493, and 3.518 eV at 15 K, respectively, for the MOCVD GaN. The spectral features are broadened and shift to lower energy as temperature increases. At room temperature (300 K), the &Ggr;V9−&Ggr;C7and &Ggr;V7(upper band) −&Ggr;C7transition energies of this wide band‐gap material are determined to be 3.420 and 3.428 eV, respectively. The temperature dependence of these two transitions have been determined using the Varshni empirical relation. Our results yieldE0(T)=3.486–8.32×10−4T2/(835.6+T) eV for the &Ggr;V9−&Ggr;C7transition andE0(T)=3.494–10.9×10−4T2/(1194.6+T) eV for the &Ggr;V7(upper band) −&Ggr;C7transition. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113820

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Measured current density was compared as a function of bias voltage for (111)B and (100) oriented resonant tunneling structures consisting of GaAlAs barriers and a GaInAs quantum well. The GaInAs quantum well is in biaxial compression. In the (111)B, but not the (100), oriented devices an electric field is generated inside the quantum well by the piezoelectric effect. It is observed that this strain generated electric field leads to a characteristic asymmetry in the current density of the (111)B oriented devices for positive and negative voltage bias. Calculations are presented that show how the piezoelectric generated electric field leads to the observed asymmetry in the current density of the (111)B oriented device and which are in qualitative agreement with the experimental observations. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113821

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

For InAs Stranski–Krastanov (SK) island growth on GaAs by molecular‐beam epitaxy, we show that the in‐plane island diameter varies exponentially with the growth temperature over the range of 390–540 °C. A transition region in SK growth between isolated island growth and island coalescing is investigated as functions of growth temperature and equivalent InAs layer‐by‐layer monolayer (ML) coverage in order to extend the isolated island regime for quantum confinement applications. InAs islands of 150 A˚ in diameter have been grown. Growth of In0.5Ga0.5As islands indicates an increased 2D epitaxial region before island nucleation and a decreased island concentration compared to growth of InAs islands. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113822

出版商:AIP    

年代:1995

数据来源: AIP