Quasi-two-dimensional electron systems in semiconductor space charge layers

A291 Surface Science 98 (1980) 135-142 0 North-Holland Publishing Company Yamada Science Foundation

ELECTRON-PHONON

and

COUPLING AND RESONANT MAGNETO-PHONON

EFFECT IN OPTICAL BEHAVIOUR

OF TWO-DIMENSIONALLY

CONFINED

CHARGE CARRIERS + Anupam MADHUKAR * and S. DAS SARMA Departments of Physics and Materials Science, California 90007, USA Received

11 July

1979;accepted

for publication

Univeristy of Southern 3 September

California, Los Angeles,

1979

Very recently enhanced electron-optical phonon coupling effects have been reported in the twodimensionally confined carriers in GaAs/Alt _,GaxAs superlattices and quantum wells. We report here the results of a study of several electron-optical phonon couplings possible in such systems. Where appropriate, zone-folding effects are explicitly taken into account. The relevance of some of these interactions to III-V compound semiconductor inversion/accumulation layers is noted. Certain special features of two-dimensional confinement in these systems make it possible to use resonant magneto-absorption studies as an unambiguous probe of these enhanced electron-phonon couplings. Results for the resonant splitting of the confined Landau level-optical phonon states are obtained within an approximation that retains only the resonant self-energy term of the upper Landau level. The resonant splitting is found to be proportional to By4 for twodimensionally confined carriers, in contrast to the By3 behavior found in threedimensional bulk semiconductors. Influence of damping and electron-light vertex correction is also discussed.

Surface Science 98 (1980) 143-144 0 North-Holland Publishing Company Yamada Science Foundation

QUASI-TWO-DIMENSIONAL

and

ELECTRON SYSTEMS IN SEMICONDUCTOR

SPACE CHARGE LAYERS Phillip J. STILES Physics Department, Received

Brown University, Providence,

Rhode Island 02912,

USA

20 July 1979

Surface Science 98 (1980) 145-153 0 North-Holland Publishing Company Yamada Science Foundation

and

PHYSICAL AND CHEMICAL PROPERTIES OF Si-SiOz REGIONS

TRANSITION

Takuo SUGANO Department of Electronic Tokyo 113, Japan Received

Engineering,

20 July 1979; accepted

the University of Tokyo 7-3-1, Hongo. Bunkyo-ku,

for publication

22 January

1980

Current understanding on physical and chemical properties of Si-SiOa transition regions is reviewed from the viewpoints of the morphology and the chemical structure of the transition

A292 region and the interface trap states. Normal and cross-sectional transmission microscopies have revealed the interface asperity which is consistent with the study of the carrier mobility in surface layers. .Various analytical measurements, such as ion-scattering spectrometry and election spectroscopy, have indicated an abrupt transition model for the Si-SiOz systems. The transition region includes strained SiO2, monolayer of SiO, as a connective region from the bulk SiO2 to Si and disordered Si layers in the Si substrate. The abrupt transition model has been used for theoretical calculation of the interface trap states originated by bonding defects, and also does not conflict with the continuous random network model for the Si-SiO2 transition region.

Surface Science 98 (1980) 154-166 0 North-Holland Publishing Company Yamada Science Foundation

and

MORPHOLOGY OF Si-Si02 INTERFACE Takuo SUGANO, Jen Jon CHEN * and Toshihisa HAMANO ** Department of Electronic Tokyo 113, Japan Received

Engineering,

8 july 1979; accepted

The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku

for publication

8 September

1979

Normal transmission electron microscopy has been carried out to study the morphology of Si-SiO2 interface, and the following results are obtained: (1) The inclusion of Si clusters in SiO2 film is found only if the final oxidation rate exceeds 10 A/min. Those Si clusters are considered to exist, being always buried within the Si substrate. (2) The faster final oxidation rate results in a rougher Si surface. The generation of Si clusters and Si-SiOz interface asperity are attributed to the diffusion model of excess Si atoms into the Si substrate. (3) The power spectral distribution of the interface asperity shows a peak value at about 40 R in the space wavelength for the transmission electronmicrograph of a SiO2 film. The measured interface asperity is consistent with the correlation length assumed in the theoretical calculations of the carrier mobility due to surface roughness scattering. (4) The correlation between the inclusion of silicon clusters within SiO2 film and the interface asperity is confumed by measuring the Hall mobility of electrons in the surface inversion layer. The different dependence on the transverse electric field is observed as expect&d from the surface roughness scattering theory for surface quantized electrons.

Surface Science 98 (1980) 167-168 0 North-Holland Publishing Company Yamada Science Foundation

and

INFLUENCE OF THE MOS SURFACE CHANNEL ON A CHANNELTO-SOURCE CONTACT DIODE CHARACTERISTIC W. HONLEIN and K. von KLITZING Physikalisches Institut der Universitiit Wiirzburg, Wiirzburg, Germany

and G. LANDWEHR Max-Planck-Institut fiir Festkorperforschung, Received

30 July 1979

F-38042

Grenoble CPdex, France