摘要:

A self‐consistent second Born aproxiamtion has been used to calculate the change in the electron and hole densities of states due to ionized donors in silicon. The results are compared with a previous partial‐wave technique and found to be in good agreement for a case of common applicability, i.e., a donor density of 1020cm−3at room temperature.

ISSN:0021-8979    

DOI:10.1063/1.332159

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The dominant deep level defects related to copper and nickel inp‐type silicon have been studied using deep level transient spectroscopy. Three acceptor states are observed in copper‐doped silicon (Ev+0.20 eV,Ev+0.35 eV, andEv+0.53 eV) and three acceptor states observed in nickel‐doped silicon (Ev+0.18 eV,Ev+0.21 eV, andEv+0.33 eV). All of these defects are neutralized by reaction with atomic hydrogen, and a concentration profile for theEv+0.18 eV Ni‐related state is given as a function of the duration and temperature of the exposure to the hydrogen plasma. Gamma irradiation produces additional donor levels atEc−0.38 eV in the copper‐doped material, and atEc−0.32 eV in the nickel‐doped material. Finally, the room temperature motion of three of the acceptor levels, Cu(Ev+0.20 eV) and Ni(Ev+0.21 eV,Ev+0.33 eV), under the influence of the electric field in a reverse biasedp‐njunction is reported. The mobilities obtained for centers associated with these three levels at 25 °C were 10−14, 6×10−15, and 2×10−15cm2 V−1 s−1, respectively.

ISSN:0021-8979    

DOI:10.1063/1.332160

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The problem of the prediction of the effective conductivity of a polycrystal given the conductivity of the single crystal is considered in the light of what can be learned from a constructible polycrystal model for which the effective conductivity can be exactly calculated. It is shown that if the only information known about the internal geometry of the polycrystal is that the aggregate is statistically homogeneous and isotropic it is not possible to narrow appreciably the well‐known ‘‘average conductivity‐average resistivity’’ bounds on the effective conductivity. The model also casts some light on the analogous problem for two phase symmetric materials.

ISSN:0021-8979    

DOI:10.1063/1.332161

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

TheI‐Vcharacteristics of amorphous arsenic telluride (As2Te3) thin film on single‐crystalline silicon substrates exhibit similarity with the characteristics of a heterojunction formed between crystalline semiconductors and the carrier transport, which involves more than one conduction mechanism at the interface. The recombination, tunnelling, and space‐charge‐limited carrier transport takes place at the interface successively, depending on the magnitude of the applied voltage. The heterojunction properties dominate at lower voltages (below 1 V), while at the higher voltages, theI‐Vcharacteristic is determined by the As2Te3film. The temperature‐dependentI‐Vcharacteristics confirm the formation of a heterojunction at the silicon‐As2Te3(film) interface. The built‐in potential evaluated from theI‐Vcharacteristics (∼0.2 V) agrees well with the observed open‐circuit photovoltageVoc. Contrary to theI‐Vcharacteristics, theC‐Vcharacteristics resemble the characteristics of a conventional metal‐insulator‐semiconductor (MIS) structure. This can be qualitatively explained by assuming the heterojunction to have a low breakdown potential (∼1.0 V), and the junction barrier capacitance in the breakdown region to be higher than either the film or the depletion capacitance.

ISSN:0021-8979    

DOI:10.1063/1.332162

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

When radiative (band to band) lifetimes and nonradiative (multiphonon via flaws) lifetimes become comparable, as is the case for GaAs, the customary diffusion equation for minority carriers under low level injection conditions must be augmented by terms originating from photon transport. Using the generalized van Roosbroeck–Shockley relation between absorption and emission as well as radiative transfer theory, the relevant equations for free carrier transport are derived. Subsequently, it is shown that the influence of the reabsorbed recombination radiation on carrier transport while unimportant at low doping levels becomes important forn‐type GaAs at high doping levels. We also determine the external luminescence flux taking due account of multiple emission and absorption events inside the sample.

ISSN:0021-8979    

DOI:10.1063/1.332163

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Surface statistics in narrow‐gap zincblende semiconductors are examined. The model employed consists of a nonparabolic conduction band and a parabolic valence band taking indium antimonide as a representative for this family of materials. The statistics of the surface space‐charge region are evaluated for a range of surface potentials and bulk concentrations using both the nonparabolic band and the standard parabolic band models. These analyses are made using the semiclassical approach.

ISSN:0021-8979    

DOI:10.1063/1.332164

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The interfacial reaction between Pt films and (100)‐orientedn‐type GaAs substrates in the temperature range between 350 and 500 °C has been studied by combining transmission electron diffraction and microscopy, glancing‐incidence x‐ray diffraction, and Rutherford backscattering spectroscopy. The reaction has produced PtGa and PtAs2. The phase PtAs2has shown a strong preferred orientation on (100)GaAs and it is the phase which dominates the contact to GaAs. The orientation relation has been analyzed by using stereographic projections. Effects of the reaction on the Schottky barrier behavior have been monitored by a combination of current‐voltage, capacitance‐voltage, and photoresponse measurements. The value of the Schottky barrier height has been determined to be 0.9 eV and no strong variation of the barrier height with annealing has been observed.

ISSN:0021-8979    

DOI:10.1063/1.332165

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

p‐GaAs (110) surfaces activated to negative electron affinity (NEA) have been examined with photoelectron spectroscopy. A typical activated GaAs surface is found to consist of both a layer of oxygen bonded to GaAs and a (Cs+,O−2) layer. The GaAs‐O layer was not anticipated prior to this work. A GaAs‐O‐Cs dipole plus the polarization of a Cs+‐O−2‐Cs+sandwich layer is proposed to explain the NEA condition based on the structure of activated surfaces found in this work. The identification of the O‐GaAs bonding layer explains the better yield achieved by the two‐step activation process compared to that achieved by a single‐step process. Possible optimization of the activation process by forming the O‐GaAs layer and the (Cs+,O−2) layer is also discussed. Adsorption of OH from the residual gas in an ultrahigh vacuum chamber is identified as one degradation mechanism of the GaAs photocathodes.

ISSN:0021-8979    

DOI:10.1063/1.332166

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

We have investigated the compatibility of TiN gate electrodes with standard metal‐oxide‐semiconductor (MOS) processing. Measurements were performed on MOS capacitors to determine the metal work function, flat‐band voltage, total interface charge density, mobile oxide charge density, oxide leakage current, and breakdown field. The measurement of the threshold voltage as a function of back bias on TiN gate MOS field effect transistors has revealed device characteristics which compare well with those of standard polysilicon gate devices.

ISSN:0021-8979    

DOI:10.1063/1.332167

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Grain‐boundary capacitance versus voltage, current versus voltage, and capacitance transient measurements are reported on lightly dopedn‐type GaAs bicrystals. The measurements are analyzed in terms of the abrupt depletion edge model in which the dominant current mechanism across the potential barrier formed by trapped charge at the interface is thermionic emission. The steady‐state measurements are completely consistent with this model and provide grain‐boundary parameters (barrier height, net carrier concentration in adjacent grains, and interface charge) necessary for interpreting capacitance transient measurements. The latter, made on a bicrystal specially selected for uniformity of the grain‐boundary barrier, reveal the presence of two closely spaced levels at 0.62 and 0.74 eV below the conduction band edge. The capture cross section associated with the dominant lower level is measured directly by two methods and falls in the range 10−14–10−13cm2.

ISSN:0021-8979    

DOI:10.1063/1.332168

出版商:AIP    

年代:1983

数据来源: AIP