Properties Of Semiconductor Surfaces Research Articles

Angle-resolved local density of states of zinc-blende semiconductor (110) surfaces: An analytic Green's-function approach

The analytic Green's function proposed by Allen and the recently developed technique for obtaining the complex band structure and the evanescent states are used to study the electronic properties of semiconductor surfaces. This approach enables one to obtain the exact solution to the surface Green's function with great computational efficiency. Angle-resolved local density of states for five (110) surfaces, including GaAs, GaP, InP, InSb, and ZnTe, are reported. All calculations are performed within a realistic ten-band tight-binding model. The effects due to surface relaxation are also discussed.

Surface photovoltage measurements and Fermi level pinning: comments on “development and confirmation of the unified model for Schottky barrier formation and MOS interface states on III-V compounds”

The theoretical concepts, experimental tools, and applications of surface photovoltage (SPV) techniques are reviewed in detail. The theoretical discussion is divided into two sections. The first reviews the electrical properties of semiconductor surfaces and the second discusses SPV phenomena. Next, the most common tools for SPV measurements and their relative advantages and disadvantages are reviewed. These include the Kelvin probe and the use of MIS structures, as well as other less used techniques. Recent novel high-spatial-resolution SPV measurement techniques are also presented. Applications include surface photovoltage spectroscopy (SPS) which is a very effective tool for gap state spectroscopy. An in-depth review of quantitative analyses, which permit the extraction of various important surface and bulk parameters, follows. These analyses include: carrier diffusion length; surface band bending, charge, and dipole; surface and bulk recombination rates; surface state distribution and properties; distinction between surface and bulk states; spectroscopy of thin films, heterostructures and quantum structures; and construction of band diagrams. Finally, concluding remarks are given.

The optical modulation of the transmission of low energy electrons: GaP surface sensitivity

When electrons are incident on a solid surface, some are backscattered and some are transmitted into the bulk of the material. This paper examines both the total transmitted current and the optically modulated component of this transmitted current for GaP. Both are dependent on the incident electron energy and this dependence is sensitive to the surface conditions. For example, Ar bombardment of the GaP surface results in a large increase in the optically modulated current compared to the polished GaP samples at higher incident electron energies (10–100 eV). Etching the GaP sample in HCl also results in a similar increase in the optically modulated current. In addition, both the HCl etch and/or Ar bombardment of the GaP surface change the temperature dependence of the optically modulated current. This surface sensitivity forms the basis for a new surface spectroscopic technique which probes the opto-electronic properties of semiconductor surfaces. A theoretical model involving the photovoltaic modulation of electron transmission is presented which can account for the observed experimental results.

Some thoughts on the existence of empty surface states and the effect of surface order on sorption

Experimental and computational information on the existence of empty surface bands in the upper portion of the band gap on nonpolar compound semiconductor surfaces is reviewed and it is shown that agreement is poor. However, both sources of information have reached the point where meaningful agreement can be achieved, thus presenting one of the first cases of quantitative experimental and theoretical self-consistency of the electronic properties of semiconductor surfaces. The dominant influence of surface atomic order on sorption at free nonpolar surfaces of compound semiconductors is also reviewed and it is suggested that both experimenters and theorists must incorporate this order-dependence into their work before a fundamental understanding of sorption can be achieved.

Semiconductor cyclotron resonance: Transport and surface phenomena

Cyclotron resonance (CR) experiments with submillimeter lasers have recently been extended to the megagauss (100 T) range. After a brief discussion of the possible origin of structure in CR data, the use of far-infrared spectroscopy in the investigation of the properties of semiconductor surfaces is reviewed. Both cyclotron resonance and inter-subband transitions have been studied. Finally, the strip-line technique which allows the observation of CR in semiconductors with high carrier concentration is discussed.

New method of influencing semiconductor surface properties : Dr. Ivan Adamcik and Dr. Josef Schrofel. Tesla Electron.4/'76, p. 113

New method of influencing semiconductor surface properties : Dr. Ivan Adamcik and Dr. Josef Schrofel. Tesla Electron.4/'76, p. 113

Determination of electrical surface properties of Si, GaAs, and CdS using acoustic surface wave

The surface properties of semiconductors can be measured by placing the sample in proximity to a surface acoustic wave delay line and applying a pulsed rf signal to the input. There will be time-dependent changes in the attenuation constant of the delay line, in the acoustoelectric voltage, and changes in the convolution voltage (if the device is a convolver) all due to the varying surface properties of the semiconductor. Further information can be obtained by subjecting the semiconductor to a pulsed dc electric field, or a second large pulsed rf field, and also by exposing the semiconductor to different wavelengths of light and repeating the above experiments. Some of the specific properties which have been determined are: (a) the location of the surface states in the energy band of epitaxial GaAs and CdS, (b) variation of the surface conductivity as a function of surface potential in Si, (c) type of surface carriers and their variation due to illumination, and (d) lifetimes associated with the emission and absorption of carriers in the surface traps. There is no physical contact with the semiconductor surface and the method is simple and sensitive.

Semiconductor surface study by transverse acoustoelectric voltage using surface acoustic waves

Electrical properties of semiconductor surfaces can be determined by measuring the transverse acoustoelectric voltage. This voltage is produced by the interaction of the surface acoustic wave propagating on a piezoelectric substrate and the carriers on semiconductor surface placed in proximity. Using 110 MHz LiNbO 3 delay lines, the transverse acoustoelectric voltage has been measured across CdS and Si, the surface properties of which are varied by different light illumination. Detailed study of the voltage waveform reveals the type of traps and the amount of charge in the traps. The method is simple, needs no contacts to the sample, and is sensitive.

Abstract: Empty surface states on semiconductors: Their interactions with metal overlayers and their relation to Schottky barriers

Within the past 2–3 years, various electron spectroscopy techniques, with electrons excited by either photons,1–6 electrons,7–9 or ions,10 have rapidly developed as probes of the electronic structure of surfaces, surface complexes, and surfaces covered with thin overlayers of metals. This development, which has as its underlying basis the surface sensitivity of electron emission in the ∠10–103 eV range (i.e., hot electron mean free paths are usually in the 3–30 A range), has accompanied parallel developments in electron energy analyzers and sources (e.g., synchrotron radiation).Alternative techniques for probing electron energy levels at solid surfaces include ultraviolet photoemission spectroscopy (UPS),1–6 x‐ray photoelectron spectroscopy (XPS),11 field emission spectroscopy (FES),12 electron‐energy‐loss spectroscopy (ELS),7,8 ion neutralization spectroscopy (INS),10 appearance potential spectroscopy (APS),9 etc. Each technique has its particular advantages and disadvantages. uv photoelectron and electr...

Determination of semiconductor surface properties using surface acoustic waves

Surface properties of semiconductors may be determined by measuring the change in attenuation constant, acoustoelectric voltage, and convolution output of a semiconductor on a lithium niobate acoustic surface wave convolver structure. The change is caused by the application of a dc pulse voltage. Experimental results are presented for both p- and n-type silicon. The method is contactless, sensitive, and requires no sample preparation except polishing of one side. Also it is possible to study the variations of the semiconductor surface states along the direction of propagation of the surface wave by proper modification of this method.

Electronic Properties of Semiconductor Surfaces

Electronic Properties of Semiconductor Surfaces

Measurements in Silicon Planar Technology: Mechanical Properties of Semiconductor Surfaces

Abstract Methods for growing silicon single crystals and then fabricating them into polished wafer form are reviewed. A survey of many of the parameters and measurement techniques needed to specify the polished surface is included. The activities of the Section on the Mechanical Properties of Semiconductor Surfaces are discussed.

ESR Study on Surface Properties of Semiconductor. II. III–V Compounds (GaAs, GaSb and InSb)

Crushed samples of III–V compounds (GaAs, GaSb and InSb) show a narrow ESR signal with g=2.0027±0.0003 after vacuum heat-treatment in vacuum. It is concluded that dipolar interaction between the ESR centers and the adsorbed O2 molecules broaden the line width and reduce the signal height. By assuming that the line broadening is proportional to the coverage of O2 molecules on the semiconductor surfaces, heat of adsorption Q is obtained for the physically adsorbed oxygen on the surface of III–V compounds; Q=1.9±0.3, 1.8±0.3 and 1.8±0.3 Kcal/mole for GaAs, GaSb and InSb respectively. The changes of the line width with air pressure suggest that some of O2 molecules on the surface condense to form O4 molecules at -150°C.

Determination of semiconductor surface properties by means of photoelectric emission

Methods for determining the electronic energy levels at and near the surface of a semiconductor with the help of experimental energy distributions of photoelectrically emitted electrons are described. Information can be obtained about the type of optical transitions responsible for the yield near threshold of clean surfaces and the significance of the photoelectric threshold, about the work function, electron affinity and ionization energy of the surface, as well as the total amount of band bending near the surface. These quantities completely characterize the energy diagram of a semiconductor surface. The above information is obtained without any assumption being made about the photoelectric emission process. It is shown that photoemission out of surface states with a density as low as 1 state per 100 surface atoms can, in principle, be measured, provided the semiconductor does not have a large concentration (> 10 17 cm −3) of impurity states in the bulk.

Electrical Properties of Semiconductor Surfaces

Electrical Properties of Semiconductor Surfaces

Two-equivalent and one-equivalent surface states

Two concepts are discussed for the control of semiconductor surface properties by chemical surface state additives. The first is that additives can be used which lead to both filled and empty states, and both are required to control the surface Fermi level. Chemically this is equivalent to adding the impurity in two different oxidation states (valences). It is shown that if one uses this approach, accurate control of the surface Fermi level should be possible for stable systems. The second concept is that it is important to distinguish between two-equivalent and one-equivalent species for use as surface states. The former are chemicals in which a relatively unstable oxidation state exists between the stable oxidation states of interest. The latter (one-equivalent) are chemicals with adjacent stable oxidation states, i.e. stable forms separated by only one electronic charge. Analysis shows that two-equivalent impurities often will behave like minority carrier trapping centers.

Physical and chemical properties of semiconductor surfaces

Physical and chemical properties of semiconductor surfaces

Limitations of the MOS capacitance method for the determination of semiconductor surface properties : K. H. Zaininger and G. Warfield. I.E.E.E. Trans. on Electron Devices, Vol. ED-12, No. 4, April 1965, p. 179

Limitations of the MOS capacitance method for the determination of semiconductor surface properties : K. H. Zaininger and G. Warfield. I.E.E.E. Trans. on Electron Devices, Vol. ED-12, No. 4, April 1965, p. 179

Limitations of the MOS capacitance method for the determination of semiconductor surface properties

For the use of the MOS capacitance method in the study of surface properties, various approximations and assumptions, of a purely conceptual and of an experimental nature, are usually made. These are not always justified. In this paper the applicability of this capacitance method for surface studies is examined critically. It is shown that this method is limited in its applicability and accuracy, and that, in most cases, it yields only the gross features of the surface states. If there are traps distributed spatially throughout the oxide, only an effective surface state distribution can be found, and this effective distribution may be interpreted ambiguously as due either to traps right at the interface, throughout the oxide, or both. Because the MOS capacitance consists essentially of the oxide capacitance in series with the semiconductor capacitances there is a practical lower limit on the magnitude of the semiconductor capacitance which can be measured. Together with difficulties in interpreting measurements in the inversion layer regime, this leads to a restriction on that portion of the forbidden gap in which states may be investigated. MOS capacitors, produced by thermal oxidation of silicon in either wet or dry oxygen, were examined by this method. It was found that, within experimental accuracy, and within the range of surface potential that can be covered by these measurements, the total number of occupied traps usually varies linearly with surface potential if it is assumed that all the traps are located right at the interface. However, these results can also be explained if it is assumed that the oxide contains a high density of low lying trap sites which are essentially uniformly distributed spatially throughout the oxide. In some specimens a monoenergetic trap level 0.7 eV below the conduction band and located at the interface was found.

Gas evolution from the surface of silicon: G. F. Romanova and I. I. Stepko, Surface Properties of Semi-conductors, Consultants Buro, New York, 1964, 56–61

Gas evolution from the surface of silicon: G. F. Romanova and I. I. Stepko, Surface Properties of Semi-conductors, Consultants Buro, New York, 1964, 56–61