摘要:

Formation of Mo/Si contacts by implantation of phosphorus ions was studied. The implantation was carried out at temperatures of −196, 25, and 150 °C and a fluence ranging between 1015and 1017ions cm−2. The morphological and structural characterizations were done with scanning electron microscopy, transmission electron microscopy, and x‐ray diffraction. Hexagonal MoSi2phase was identified in samples implanted with more than 1016ions cm−2at all three implantation temperatures. Traces of MoP were found in the sample implanted with 1017ions cm−2at 150 °C. Measured effective contact resistance showed ohmic behavior in as‐implanted samples except for samples implanted with 1015ions cm−2at 150 °C. Smooth surfaces of implanted MoSi2structures remained after post‐implant annealing at 850 °C for 1/2 h in H2ambient. The effect of post‐implant annealing is also discussed in terms of doping, microstucture, and contact resistance.

ISSN:0021-8979    

DOI:10.1063/1.329268

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Growth of GaInAs and A1InAs by molecular beam epitaxy on idium phosphide substrates is reported. Unintentionally doped, closely lattice matched GaInAs layers weren‐type with &mgr;300up to 8800 cm2 V−1 s−1andnas low as 1×1016cm−3whereas undoped A1InAs layers were typically high resistance. 2‐MeV Rutherford backscattering showed good GaInAs crystal quality although the A1InAs was somewhat disordered. Evidence for cation exchange at interfaces and surface accumulation of indium was evident from both RBS and sputter Auger profiles.Insitugrown A1 films on A1InAs showed an effective barrier height∼0.8 eV from 1/C2V s V curves, however attention to the forwardI‐Vcharacteristics indicated lower values. DLTS results indicate the GaInAs to be virtually trap‐free but that A1InAs has high deep level concentrations owing to low growth temperatures. Good photoluminescent efficiencies were demonstrated for GaInAs layers, however, poor results were obtained for A1InAs.

ISSN:0021-8979    

DOI:10.1063/1.329212

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Channeling and transmission electron microscopy have been used to investigate the parameters that govern the extent of damage in ion‐implanted GaAs and the crystal quality following capless furnace annealing at low temperature (∼400 °C). The implantation‐induced disorder showed a strong dependence on the implanted ion mass and on the substrate temperature during implantation. When the implantation produced a fully amorphous surface layer the main parameter governing the regrowth was the amorphous thickness. Formation of microtwins after annealing was observed when the initial amorphous layer was thicker than 400 A˚. Also, the number of extended residual defects after annealing increased linearly with the initial amorphous thickness and extrapolation of that curve predicts good regrowth of very thin (<400 A˚) GaAs amorphous layers produced by ion implantation. A model is presented to explain the observed features of the low‐temperature annealing of GaAs.

ISSN:0021-8979    

DOI:10.1063/1.329213

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Phase formation has been studied in Au‐Al thin‐film interactions by means of4He+MeV backscattering and x‐ray diffraction techniques. The films were annealded at temperatures low enough for no liquid phase formation. Au4Al, Au5Al2, Au2Al, AuAl, and AuAl2were detected from samples prepared by depositing the exact stoichiometry quantities of Au and Al. The phase formation sequence was determined. The first phase formed is Au5Al2; the others are observed with the disappearence of one phase previously formed. For instance, Au4Al grows only when all Al is reacted and, on the other hand, AuAl2when all Au is reacted. The sequence of the phases in the Au‐Al interactions cannot be interpreted on the basis of pure thermodynamic or kinetic arguments and a composite mechanism is proposed.

ISSN:0021-8979    

DOI:10.1063/1.329214

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Thin Pt, Pd, Pt2Si, and Pd2Si films deposited on Si were reacted by using electron beam pulses of 60 nsec duration in the 0.4–2.4 J/cm2energy density range. Irradiaton of Pd/Si structure produces at the same time PdSi, Pd2Si, Pd3Si, and Pd4Si, while PdSi is the only phase observed starting from the Pd2Si/Si structure. Post‐thermal annealing of these layers up to 600 °C induces the growth of Pd2Si phase at the expense of the other phases. PdSi seems to be a metastable phase at least up to 600 °C. PtSi, Pt2Si, Pt3Si compounds are formed after irradiation of Pt/Si structure. Post‐thermal annealing at 500 °C produces PtSi. A Si‐enriched metastable phase Pt2Si3is present after irradiation of Pt2Si/Si or PtSi/Si structure. Post‐thermal annealing at 450 °C produces the growth of Pt2Si3. Further annealing at 500 °C induces the formation of PtSi and Si polycrystal.

ISSN:0021-8979    

DOI:10.1063/1.329253

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Ohmic contacts ton‐GaAs using a Ge/GaAs heterojunction have been developed. Ge layers with free‐electron concentrations above 1×1020cm−3have been grown on GaAs by molecular beam epitaxy (MBE). Gold evaporated on such structures forms tunnel contacts through the Ge to the GaAs. The lower barrier height of metals on Ge compared to GaAs and the small barrier at the Ge/GaAs heterojunction facilitates the formation of contacts with specific contact resistances below 10−7&OHgr; cm2.

ISSN:0021-8979    

DOI:10.1063/1.329254

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Neutron transmutation doping provides a convenient means to shift the doping level and the Fermi energy in semiconductors. In order to understand this shift quantitatively, the position of the Fermi energyEFas a function of the doping levelC[EF(C) characteristic] is calculated and discussed for semiconductors with arbitrary distribution of localized levels. It is shown how theEF(C) characteristic depends on the presence of defect levels in the forbidden gap. In particular,EFis pinned at energy with large density of localized levels, corresponding to a high stability ofEFagainst variations ofC. A quantitative measure of this stability is introduced with the derivativekTdC/dEFfor theEF(C) characteristic. This leads to a new method to determine experimentally the energetic position and concentrations of defects in semiconductors. The method seems to be applicable not only to crystalline semiconductors such as Si or GaAs but also to amorphous silicon.

ISSN:0021-8979    

DOI:10.1063/1.329255

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

We have studied the disappearance of impurity levels in silicon and germanium due to free‐carrier screening of the Coulomb field of the impurity ions. The ground‐state eigenfunctions and eigenvalues have been calculated for electrons described by an ellipsoidal effective‐mass Hamiltonian. A two‐dimensional finite‐element analysis was used to obtain the solutions. Only moderate carrier densities (1019cm−3for silicon and 1018cm−3for germanium) are needed to cause the impurity levels to disappear into the conduction band, the result at high doping densities being simply a degenerate semiconductor.

ISSN:0021-8979    

DOI:10.1063/1.329256

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A quantitative picture of the geometric and energetic trap structure of positively corona charged polyfluoroethylenepropylene (Telfon FEP‐A) was obtained by a combination of isothermal and thermally stimulated current measurements in ’’open circuit.’’In addition the heat‐pulse method was used to determine the mean depth and the total charge in the sample. Application of these methods allows conclusions about the trapping probability in deep volume traps and the loss of charge in the sample due to neutralization of positive carriers at the electrodes. E/T;8172.20Jv, 73.60Hy, 71.20+c, 71.70.Ms

ISSN:0021-8979    

DOI:10.1063/1.329257

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A method for determining the geometrical surface trap structure of highly insulating polymer films is presented. We compare ’’open‐circuit’’ thermally‐stimulated current measurements of corona and electron‐beam‐charged foils. We present the results for three different polymers: polyfluoroethylenepropylene [Teflon (FEP)], polyethyleneterephthalate [Mylar (PET)], and Polyethylene (PE). For Teflon one observes that the surface traps are energetically shallower than the bulk traps, for Mylar no separate surface traps exist whereas for polyethylene the situation is opposite to Teflon. The spatial resolution of the method is 0.5 &mgr;m.

ISSN:0021-8979    

DOI:10.1063/1.329258

出版商:AIP    

年代:1981

数据来源: AIP