Semiconductor Inversion Layers Research Articles

Ionization probability of the bound impurity states of two-dimensional electrons under strong magnetic and finite electric fields

The ionization probability of the bound impurity states in a semiconductor inversion layer under strong magnetic fields H is calculated as a function of temperature and electric field value E. The conditions for relatively large ionization probability are determined. The possibility of the bound state ionization must be taken into account for the interpretation of the inversion layer properties at the Shubnikov-De Haas conductivity minima.

Quantum size effects on the plasma dispersion in quasi-two-dimensional electron systems

A generalized many-body dielectric theory is developed for studying the collective excitation spectrum in quasi-two-dimensional electron systems in semiconductor inversion and accumulation layers and in semiconductor heterostructures and superlattices. In particular, the coupling between the intrasubband and intersubband collective modes (plasmons) is explicitly retained in the theory. This mode-coupling effect modifies the plasma dispersion relation in these systems and the theory explains the hitherto unexplained phenomenon of a plasmon mass increase at higher wave numbers observed in silicon inversion layers. In a superlattice this mode-coupling effect produces a leading-order modification of the plasma dispersion relation in contrast to other mode-coupling-type phenomena (which are usually higher-order processes away from resonance) giving rise to an improved agreement between the theory and light-scattering experimental results.

Theory of optical transitions in inversion layers of narrow-gap semiconductors

The theory of electric sub-bands in MOS structures involving InSb-type narrow-gap semiconductors is developed and used to resolve a long-standing problem concerning a possibility of inter-sub-band resonance excitations with light polarisation parallel to the interface. k.p p theory is formulated for electrons in inversion layers, taking into account the main features of the InSb-type band structure and assuming a triangular model potential near the interface. It is shown that the interband k.p coupling and the small value of the gap make it possible to excite inter-sub-band optical transitions with light polarisation parallel to the interface. The transition probability is proportional to k/sub ///2, where k/sub /// is the electron wavevector parallel to the interface. Numerical estimations are carried out using variational functions for electric sub-bands. For typical experimental conditions in InSb MOS structures one obtains the optical transition probability for parallel light polarisation to be a few percent of that for the transverse one. Both the k/sub ///2-dependence and the numerical values agree with existing experiments. The possibility of excitation with parallel light polarisation is interpreted in terms of an analogy between free relativistic particles and electrons in narrow-gap semiconductors.

Microscopic theory of excitonic effects in semiconductor inversion layers

Microscopic theory of excitonic effects in semiconductor inversion layers

Microscopic theory of excitonic effects in semiconductor inversion layers

Microscopic theory of excitonic effects in semiconductor inversion layers

Surface roughness induced scattering and band tailing

A random potential due to surface roughness has long been recognized as the dominant scattering mechanism at high electron concentrations in quantized inversion layers of semiconductors, but little definitive understanding is truly available. Here, the extent of band tailing and the role of this band tailing in electron transport have been estimated from the second-order correction to the surface subbands arising from the surface roughess induced random potential. Surface roughness parameters were determined from high resolution TEM pictures of the Si-SiO 2 interface and are found to be in reasonable agreement with earlier estimates. Calculations based upon these parameters indicate that band tailing is important at high inversion layer densities (≳ 10 12 cm 2 ).

On the surface recombination current of metal-insulator semiconductor inversion layer solar cells

Current voltage characteristics have been obtained under dark and illuminated conditions for Al-SiO2-pSi metal-insulator semiconductor inversion layer solar cells. The cells were fabricated on <100≳ and <111≳ oriented substrates with resistivities in the range of 8–15 Ω cm. For <111≳ cells the open circuit voltages Voc were found to be lower than for <100≳ cells. The measured differences in Voc were higher than expected from the dark characteristics which is explained as a difference in the surface recombination current due to a higher interface state density Nss of <111≳ cells.

Effect of impurities on the two-dimensional electron gas polarisability

The polarisability for a two-dimensional electron gas is calculated in the presence of impurities by a Green function formalism. This leads to a system with finite mean free path due to electrons scattering off impurities. The calculated polarisability is found to be strongly dependent on the mean free path. The main feature is the suppression of the sharp corner at wavevector 2kF for finite mean free paths, and the pure metal result is recovered for the infinite mean free path. A possible application of the results of the transport properties of semiconductor inversion layers is discussed.

Collective modes of spatially separated, two-component, two-dimensional plasma in solids

Longitudinal collective spectrum of a spatially separated, two-component, two-dimensional plasma is investigated using a generalized random-phase approximation. Such plasmas can be realized in semiconductor heterojunctions, superlattices, and inversion or accumulation layers. In general two modes are found to exist: the one with energy proportional to $\sqrt{q}$ at long wavelengths is the usual optical plasmon and the other with energy proportional to $q$ at long wavelengths is the acoustic plasmon. It is shown that the spatial separation between the two charge components makes it possible for the acoustic branch to move out of the electron-hole continua of both the components provided it exceeds a critical value. Consequently the acoustic-plasmon mode is totally undamped at long wavelength. The dynamic structure factor of the system is analyzed and the feasibility of observing an acoustic plasmon in GaAs-${\mathrm{Ga}}_{x}{\mathrm{Al}}_{1\ensuremath{-}x}\mathrm{As}$ double quantum well is discussed.

Many-body effects in the Si metal-oxide—semiconductor inversion layer: Subband structure

Many-body effects in the Si metal-oxide—semiconductor inversion layer: Subband structure

Effect of the electron-phonon interaction on the subband structure of inversion layers in compound semiconductors

Recently electron inversion layers have been fabricated on a number of compound (principally III–V) semiconductors. Because of the polar nature of these materials, the effect of the electron-optical phonon interaction is expected to be significant. This has certainly been true in recent calculations of the ground state energy and equilibrium density of electron-hole liquids in a number of compound semiconductors [1]. We have calculated the subband structure of inversion layers in polar semiconductors. The starting point of our many-body calculation is the Hartree subband structure determined using a variational method described in ref. [2]. Using the Hartree wavefunctions as basis functions we have calculated the self-energy of the ground and first excited subbands to lowest order in the effective interaction. This interaction is the sum of Coulomb (direct and image) and electron-phonon terms which are screened by a dielectric function that includes both e-e and e-ph effects. The screening by inversion layer electrons has been treated in the plasmon-pole approximation. We have obtained the electron self-energy, the quasi-particle energy, and the subband separations as a function of inversion layer concentration for parameters corresponding to GaAs. The coupling of electrons to bulk phonons is considered. Our results are compared to those obtained using the simpler ϵ 0 ∗ approximation [1]. Here, explicit phonon terms are neglected, but the bare band mass is replaced by the polaron mass, and the high frequency dielectric constant (ϵ ∞) is replaced by the static dielectric constant (ϵ 0). This approximation has been applied to the electron-hole liquid for situations in which the optical phonon frequency is larger than the electron plasma frequency. The idea behind the ϵ 0 ∗ approximation is to account in a very rough way for vertex corrections to the electron-phonon interaction. A principal criticism of our dynamic RPA calculations is the neglect of vertex corrections in the effective interaction. In three-dimensional metallic systems (high density), Migdal's theorem applies and vertex corrections are small. However, it is not clear that we may neglect such corrections in inversion layers. This point will be discussed further.

Effect of the electron-phonon interaction on the subband structure of inversion layers in compound semiconductors

Effect of the electron-phonon interaction on the subband structure of inversion layers in compound semiconductors

Influence of surface electric field on the MOS capacitance of n-channel inversion layers in small gap semiconductors

physica status solidi (a)Volume 59, Issue 1 p. K69-K74 Short Note Influence of surface electric field on the MOS capacitance of n-channel inversion layers in small gap semiconductors D. R. Choudhury, D. R. Choudhury Institute of Radio Physics and Electronics, University College of Science and Technology, Calcutta Search for more papers by this authorA. K. Chowdhury, A. K. Chowdhury Institute of Radio Physics and Electronics, University College of Science and Technology, Calcutta On leave of absence from the Department of Physics, Patna University, Patna, India.Search for more papers by this authorA. N. Chakravarti, A. N. Chakravarti Institute of Radio Physics and Electronics, University College of Science and Technology, Calcutta Search for more papers by this author D. R. Choudhury, D. R. Choudhury Institute of Radio Physics and Electronics, University College of Science and Technology, Calcutta Search for more papers by this authorA. K. Chowdhury, A. K. Chowdhury Institute of Radio Physics and Electronics, University College of Science and Technology, Calcutta On leave of absence from the Department of Physics, Patna University, Patna, India.Search for more papers by this authorA. N. Chakravarti, A. N. Chakravarti Institute of Radio Physics and Electronics, University College of Science and Technology, Calcutta Search for more papers by this author First published: 16 May 1980 https://doi.org/10.1002/pssa.2210590169Citations: 6 92, Acharya P. C. Road, Calcutta 700009, India. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume59, Issue116 May 1980Pages K69-K74 RelatedInformation

Spectroscopy of semiconductor inversion layers in high magnetic fields

Inversion layers on semiconductors are nearly ideal systems to investigate the electronic properties of a two-dimensional electron gas (2DEG). With infrared spectroscopy several resonance excitations of the 2DEG are studied, such as intersubband resonance, cyclotron resonance, combined resonances, electron-spin resonance, and plasmons. Selected results of such investigations and their implications for the electronic properties of the 2DEG are reviewed with special emphasis on high magnetic field experiments. The discussion is centered around the characteristically different semiconductors Si, InSb and PbTe.

Low-lying collective modes in the charge density wave state inn-type inversion layers of semiconductors

Acoustic-phonon like low-energy long-wave length collective excitations are shown to exist in the charge density wave (CDW) ground state of a two-valley model forn-type inversion layers. The dispersion of the collective modes are obtained by calculating the two-particle Green's function within the random phase approximation, and the “sound velocity” is investigated as a function of interaction parameters and temperature. Physically the modes represent the phase oscillation of the CDW and the fluctuation of the population difference between two valleys; these two modes are coupled to each other.

Two-valley model for studying the low temperature phases inn-type inversion layers of semiconductors

The low temperature phases of a two-valley model forn-type inversion layers are studied. If the coupling constants are in a certain range charge-density waves exist below a transition temperatureT c. For reasonable values of the coupling constantsT c is around 30 °K.

On the modification of the Einstein relation for semiconductor inversion layers in the presence of a quantizing magnetic field

On the modification of the Einstein relation for semiconductor inversion layers in the presence of a quantizing magnetic field

Electronic ground state of inversion layers in many-valley semiconductors

We present a self-consistent many-body calculation of the possible ground states in the inversion layers of many-valley semiconductors (as typified by Si) in the metal-oxide-semiconductor configuration. A complex phase diagram results when the various electronic interactions are regarded as free parameters; for experimentally reasonable values, a charge-density wave is the ground state at the Si(111)-Si${\mathrm{O}}_{2}$ interface with the experimentally observed valley degeneracy and cyclotron mass. At the Si(100)-Si${\mathrm{O}}_{2}$ interface, the paramagnetic state remains stable over the experimentally accessible region of the phase diagram. Applications to other systems are briefly mentioned and experimental tests of the theory are suggested.

Optical properties of charge-density-wave ground states for inversion layers in many-valley semiconductors

A charge-density-wave ground state satisfactorily accounts for the experimentally observed occupied valley degeneracy, high cyclotron mass and stress-dependent anisotropic conductivity in inversion layers at the Si(111)-Si${\mathrm{O}}_{2}$ interface. We make specific predictions about anisotropic optical transitions, the observation of which would distinguish the density-wave model from any alternative explanations of the experimental data.

On the absorption of infrared radiation by electrons in semiconductor inversion layers : S. J. Allen and D. C. Tsui. Solid-St. Commun.20, 425 (1976)

On the absorption of infrared radiation by electrons in semiconductor inversion layers : S. J. Allen and D. C. Tsui. Solid-St. Commun.20, 425 (1976)