摘要:

In this letter, we report on the high resolution patterning of a silicon surface without using a resist layer. A hydrogen passivated silicon surface is chemically modified by illumination with ultraviolet light (UV, &lgr;=350.7 nm) in air. Auger electron spectroscopy (AES) revealed that silicon oxide was formed at the illuminated areas. A light interference pattern was made on the silicon surface by two UV laser beams, oxidation occurred only at the maximum intensity, but not at the minimum. In this way oxide lines were fabricated with a width below 200 nm on a 500 nm period. The oxide lines were used as a wet etch mask to etch more than 25 nm into Si(110) without affecting the oxide. The advantage of this technique is that it is a very simple process which allows the high resolution patterning over large areas of silicon without using a resist. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114835

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The gettering behavior of Cu and Fe in ion beam synthesized silicon on insulator (SOI) material incorporating a buried oxide layer is investigated before and after the formation of deep gettering zones by either C or He implantation. Secondary ion mass spectroscopy (SIMS) analysis is employed to obtain information as to the C, O, Fe, and Cu depth distributions. It is shown that the proximity gettering approach using C and He renders the possibility of removing and stabilizing metal contaminants not only away from the near‐surface region, but also remote from the buried oxide/substrate interface to which they normally segregate in the absence of efficient implantation induced gettering sinks. C implants are found to have better gettering efficiency as they getter both Cu and Fe whereas He implants getter Cu only. In addition, the C implant dose needed to achieve one and the same gettering effect is an order of magnitude lower than the He dose. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114929

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have studied the rapid degradation of the AlGaAs/GaAs single quantum well laser diodes on Si substrates grown by metalorganic chemical vapor deposition. The dislocations propagate at velocities up to ∼75 &mgr;m/h along ⟨100⟩ and ∼20 &mgr;m/h along ⟨110⟩, which cause an increase in threshold current and a decrease in differential quantum efficiency. The degraded current–voltage characteristic resulted from the defect‐assisted impurity diffusion. The degradation process occurs very rapidly due to the presence of a high density of defects and thermally induced strain. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114930

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Tungsten (W) films are deposited on sputter‐deposited TiN adhesion layers in a cold‐wall chemical vapor deposition reactor, initiated with the deposition of a W nucleation layer by SiH4reduction of WF6. H2is also introduced in the reactor for some depositions. The electrical resistivity and mechanical stress of the W films are found to be dependent on the underlying TiN layers as well as on the presence of H2during W nucleation layer deposition. A higher resistivity is obtained when the W is deposited on the TiN prepared at 250 °C than on the TiN prepared at 450 °C. For the W deposited on the low‐temperature TiN, the resistivity is reduced by adding H2to the reactants during W nucleation layer deposition; while for the W deposited on the high‐temperature TiN, the resistivity is almost insensitive to the H2addition. More oxygen and fluorine are found at the W–TiN interface for the W deposited on the low‐temperature TiN than on the high‐temperature TiN. Introduction of H2to the reactants during W nucleation layer deposition reduces the concentrations of interfacial fluorine and oxygen, in agreement with thermodynamic predictions. A lower film stress is obtained for the W deposited on the high‐temperature TiN layers and/or with H2addition. The W films become less textured when H2is introduced to the reactants during W nucleation layer deposition. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114931

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

0.1% B2H6diluted in hydrogen is used as thep‐type dopant gas in Si1−xGexgrown by ultrahigh vacuum chemical vapor deposition (UHVCVD) using Si2H6and GeH4. The boron concentration is evaluated by secondary ion mass spectrometry (SIMS). The boron concentration of Si1−xGexincreases with the increase of the GeH4flow rate, that is, Ge fraction, by keeping Si2H6and B2H6flow rates constant. The result may be due to the increase of the vacant surface sites which is caused by the increase of the hydrogen desorption rate when a higher Ge fraction epilayer is grown. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114932

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The electrical properties of semi‐insulating InP epitaxial layers grown by metalorganic chemical vapor deposition using CCl4as a doping source have been studied as a function of the growth conditions of the material. Secondary ion mass spectrometry has been used to analyze the incorporation of impurity species in these layers. These measurements indicate that the resistivities of the CCl4‐doped InP layers increase exponentially (exceeding 1012&OHgr; cm) with increasing growth temperature. The incorporation of C, H, and Cl decreases in these layers. In conjunction with the dependence of the resistivity on the flow rate of the diluted CCl4dopant during growth, these results suggest that the semi‐insulating nature of the InP layers is due to CCl4‐mediated incorporation of one or more defects during growth. It is not likely that either a deep level created by Cl or hydrogen passivation of shallow donors and acceptors is responsible for the electrical properties of this material. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114933

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Electron beam induced current experiments in the planar geometry are performed on Mo/CuInX2/CdS/ZnO thin film solar cells where X is S, Se. We measure the collection efficiency of cells as a function of the beam energy and subsequently identify the depth dependent collection function. For CuInS2devices an effective diffusion length of 1.0±0.1 &mgr;m and a depletion layer of 0.05±0.03 &mgr;m is determined. The collection function of a CuInSe2cell points towards a low recombination rate at the back contact and a diffusion length exceeding 3 &mgr;m. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114934

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

An analysis procedure for real time spectroscopic ellipsometry data is described that allows one to characterize compositional gradients in thin films prepared by continuously varying the deposition parameters. This approach provides the time evolution of (i) the instantaneous deposition rate, (ii) the surface roughness layer thickness, and (iii) the near‐surface dielectric function and composition of the film with a depth resolution as high as 7 A˚. We apply the analysis to obtain the depth profile of the relative void volume fraction for an amorphous silicon‐carbon alloy film prepared by plasma‐enhanced chemical vapor deposition. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114935

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We present gain calculations for ideal bulk GaN and 100 A˚ GaN quantum well laser structures. We show that due to the large electron and hole effective masses in GaN, the room‐temperature material gain characteristics of a 100 A˚ quantum well are a little different from those of bulk GaN up to a gain level of 1000 cm−1, and that the transparency and threshold carrier density is approximately 2.5 times that in an equivalent GaAs structure, with the radiative current density being of order eight times larger. Comparing the unstrained zinc blende and wurtzite crystal structures, we predict improved gain characteristics in the wurtzite case. The introduction of compressive strain, e.g., through pseudomorphic growth between unstrained AlGaN barriers, will benefit both crystal structures, with wurtzite remaining better than zinc blende for mismatch up to about 1.5%. Finally, we note that the gain characteristics would be further improved if it were possible to grow tensile‐strained zinc blende layers. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114936

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report on the application of deep level transient spectroscopy to the study of electron emission from quantum dots. The results are presented for coherently grown InP dots embedded in Ga0.5In0.5P. We determine an emission activation energy of 220 meV for the one electron ground state of the dots. With increased average electron occupation in the dots we observe a systematic shift of the DLTS peak towards lower temperatures. This we interpret as being due to Coulomb charging of the dots. We extract an average Coulomb charging energy of 8–12 meV per added electron in the dot in agreement with our estimated value of 9 meV. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114937

出版商:AIP    

年代:1995

数据来源: AIP