摘要:

Optical emission studies of the glow‐discharge deposition ofa‐Si:H alloys reveal the presence of reactive species derived from process gases and impurities. Studies of the dependences of emission intensities upon depositon parameters elucidate the mechanisms of formation of these species. Effects of impurities detected by emission spectroscopy upona‐Si:H film electronic properties are discussed. A model of the chemical reactions involved in film growth is presented.

ISSN:0094-243X    

DOI:10.1063/1.33076

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Compared to SiH4, the plasma deposition of amorphous hydrogenated silicon from Si2H6results in compositionally similar films, deposited at rates at least an order of magnitude higher. The films also display larger dark and photoconductivties, a result related directly to higher Efin the intrinsic Si2H6‐prepared material. The effect is structural, not impurity‐dominated. Dopant incorporation is also found to be strongly influenced by the silicon source, as is the doping efficiency. For a given gas phase concentration of n‐type dopant (PH3), the distribution coefficient is Ceff<1 for Si2H6plasmas, compared to Ceff≳1 for depositions from SiH4, yet film electrical properties are comparable. On the p‐type side, much smaller differences are observed with B2H6doping of the two sources. Finally, a‐Si:H plasma deposition chemistry is examined within the context of a neutral radical model and hydrogen etching experiments.

ISSN:0094-243X    

DOI:10.1063/1.33027

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Optical emission spectra from the silane plasma have been measured as a function of silane flow rate. The relative concentrations of the emissive species, SiH (414 nm), Si (288 nm), and H (656 nm), have been determined. The growth rate and vibrational spectra of the resulting films are interpreted in terms of the emission intensities of the SiH and H radicals, and the diffusional mass transport of these neutral radicals is suggested to be responsible for the deposition process of a‐Si:H. From the optical emission spectroscopy of doping gases, decompostion rate of diborane is found to be much less than that of phosphine. Extremely high doping efficiencies of boron and phosphorus atoms have been realized by lowering the emission intensity of the SiH band with respect ot the H2line.

ISSN:0094-243X    

DOI:10.1063/1.33083

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A model which suggests that a‐Si films deposited from (SiF4+H2) mixtures are subjected to strong ionic etching during growth is proposed. It is shown that many of the properties of these a‐Si films, such as high conductivity in doped layers and growth, H incorporation, and bandgap data, can be explained by this model. High conductivities are achieved without any detectable F in the film.

ISSN:0094-243X    

DOI:10.1063/1.33067

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The dependence of hydrogen content, on the partial pressure of hydrogen, substrate bias, deposition rate, and deposition temperature was found to be consistent with a kinetic model of hydrogen incorporation into a‐SiHxfilms, produced by reactive sputtering in an Ar+H plasma.

ISSN:0094-243X    

DOI:10.1063/1.33079

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

We investigate the differences between sputter (S) produced and representative plasma decomposition (GD) produced a‐Si:H in electron drift mobility activation energy, photoluminescence temperature quenching and peak energy, optical absorption extended by photoconductivity, and midgap state density from conductance/capacitance measurements. From these property measurements we conclude that for the GD material less modification of the bands occurs for the hydrogenation required to obtain a comparable midgap state density. This density, measured in both materials, is larger than that expected from an extrapolation of the band tails.

ISSN:0094-243X    

DOI:10.1063/1.33042

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Fast real time ellipsometry has been performed to follow the growth of a‐Si:H films deposited in a low pressure D. C. discharge of silane. First results show that the growth is incompatible with a simple homogeneous layer by layer mechanism and suggest the presence of microstructure.

ISSN:0094-243X    

DOI:10.1063/1.33056

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

This paper shows how electronic transport properties of a‐Si:H alloys are modified through the application of electric and magnetic d.c. fields during the film formation. The films studied have been produced by capacitive and inductive r.f. glow discharge (3% SiH4in Ar). The photoconductivity and the density of defect states are greatly improved if a d.c. magnetic field is applied, perpendicular to the direction electric of d.c. field. A comparative study between the electronic transport properties of the films produced using the two techniques will be presented.

ISSN:0094-243X    

DOI:10.1063/1.33060

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The details of plasma characteristics, chemistry and its relationship to the nucleation and growth process of glow discharge a‐Si:H remain unresolved. RF substrate bias is explored as a major influence on the deposition of amorphous Si:H. Recent investigations have revealed the importance of silane ion chemistry and surface chemical reactions in the process of flim growth. Experiments, including those with various inert gas diluents, indicate the importance of various ionic and neutral SixHyspecies in plasma‐deposited a‐Si:H films. The bias voltage on the substrate is induced by the r.f. plasma as a result of the difference in electron and ion mobilities in the plasma. The magnitude of the induced bias voltage is significantly dependent upon the geometry of the deposition system. Different substrate voltages are generated by tuning the r.f. substrate circuit and by feeding r.f. power directly through the substrate. Films have been grown under a wide range of bias voltages, both positive and negative, and in different gas mixtures of SiH4/Ar, SiH4/He, and PH3doped SiH4. The effects of substrate bias on films characterized by their luminescence, I.R. spectra, optical absorption and morphology are discussed.

ISSN:0094-243X    

DOI:10.1063/1.33061

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

a‐Si‐H films are sputtered from a Si target in an argon‐hydrogen atmosphere. It has been found that the bias voltage induced on the heated substrate by the r.f. plasma influences film growth and has a profound effect on the properties of the a‐Si‐H. The photoconductivity of the films increase to a maximum and then decrease with increasing bias voltage applied to the substrate during growth. Although the hydrogen content of the films does not change significantly with bias, the variation in the relative magnitude of the vibrational stretching bands at 2000 and 2100 cm−1appears to correlate with the photoconductivity bias dependence. The deposition rate and optical absorption edge decreases monotonically with increasing bias.

ISSN:0094-243X    

DOI:10.1063/1.33062

出版商:AIP    

年代:1981

数据来源: AIP