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Comparison of reflectance difference spectroscopy and surface photoabsorption used for the investigation of anisotropic surfaces
A41 2 Surface Science 287/288 (1993) 686-692 North-Holland
Comparison of reflectance difference spectroscopy and surface photoabsorption used for the investigation of anisotropic surfaces K. Hingerl a,b, D.E. Aspnes a and I. Kamiya ~,b " Bell Communication Research, Red Bank, NJ 07701-7040, USA b Physics Department, University of Illinois, Urbana, IL 61801, USA Received 7 September 1992; accepted for publication 19 November 1992 Reflectance difference spectroscopy (RDS) and surface photoabsorption (SPA) are two optical characterization techniques that are now in common use for monitoring and controlling epitaxiat growth. Here we establish the connection of SPA data to the surface dielectric response, using an anisotropic three phase model (substrate, anisotropic overlayer, ambient). In contrast to the generally accepted picture, our calculations show, that the contribution to the SPA signal from the dielectric component normal to the surface is negligible, and that the major contribution arises from the projection of the dielectric tensor on the line formed by the intersection of the surface and the plane of incidence. It follows, that the difference between SPA data taken with the plane of incidence along the different principal axis is related to, and in fact can be calculated from, RDS spectra. By comparing published data to our database of RD spectra, we are able to find the surface reconstruction present during flow modulated organo metallic chemical vapour epitaxial growth of GaAs epilayers.
Surface Science 287/288 (1993) 693-698 North-Holland
Theory of second-harmonic generation at semiconductor surfaces M. Cini, R. Del Sole Dipartimento di Fisica, Universita' degli Studi di Roma "Tor Vergata", via della Ricerca Scientifica 1, 00133 Roma, Italy
and Lucia Reining Centre Europ~en de Calcul Atomique et Mol~culaire, B~t. 506, Universit~ Paris Sud, Orsay, France Received 1 September 1992; accepted for publication 19 November 1992 We outline a method to determine the intensity of the second harmonic emitted from a semiconductor surface. Calculations have been carried out for Si(111)/As and compared with second-harmonic generation experiments carried out on the same surface.
Surface Science 287/288 (1993) 699-702 North-Holland
Linear and non-linear optical properties of surfaces and spatially non-local potentials E. Piparo and R. Girlanda Istituto di Struttura della Materia, Facolt~ di Scienze m.fn., Universit~ di Messina, salita sperone 31, C.P. 57, 1-98166 Sant'Agata, Messina, Italy Received 1 September 1992; accepted for publication 19 November 1992 We have developed a theory of the random phase approximation (RPA) optical response of surfaces and interfaces that, in the supercell approximation, takes into account the possible non-locality in the effective potential. One can greatly simplify the theory by decomposing the perturbing electric field into an almost spatially constant external field and an induced z-dependent part; A self-consistent solution of Maxwell equations allows us to express the first and second order in the external field z-dependent densities of polarization by means of "effective" first and second order z-dependent susceptibilities for which approximated expressions are given.
Comparison of reflectance difference spectroscopy and surface photoabsorption used for the investigation of anisotropic surfaces K. Hingerl a,b, D.E. Aspnes a and I. Kamiya ~,b " Bell Communication Research, Red Bank, NJ 07701-7040, USA b Physics Department, University of Illinois, Urbana, IL 61801, USA Received 7 September 1992; accepted for publication 19 November 1992 Reflectance difference spectroscopy (RDS) and surface photoabsorption (SPA) are two optical characterization techniques that are now in common use for monitoring and controlling epitaxiat growth. Here we establish the connection of SPA data to the surface dielectric response, using an anisotropic three phase model (substrate, anisotropic overlayer, ambient). In contrast to the generally accepted picture, our calculations show, that the contribution to the SPA signal from the dielectric component normal to the surface is negligible, and that the major contribution arises from the projection of the dielectric tensor on the line formed by the intersection of the surface and the plane of incidence. It follows, that the difference between SPA data taken with the plane of incidence along the different principal axis is related to, and in fact can be calculated from, RDS spectra. By comparing published data to our database of RD spectra, we are able to find the surface reconstruction present during flow modulated organo metallic chemical vapour epitaxial growth of GaAs epilayers.
Surface Science 287/288 (1993) 693-698 North-Holland
Theory of second-harmonic generation at semiconductor surfaces M. Cini, R. Del Sole Dipartimento di Fisica, Universita' degli Studi di Roma "Tor Vergata", via della Ricerca Scientifica 1, 00133 Roma, Italy
and Lucia Reining Centre Europ~en de Calcul Atomique et Mol~culaire, B~t. 506, Universit~ Paris Sud, Orsay, France Received 1 September 1992; accepted for publication 19 November 1992 We outline a method to determine the intensity of the second harmonic emitted from a semiconductor surface. Calculations have been carried out for Si(111)/As and compared with second-harmonic generation experiments carried out on the same surface.
Surface Science 287/288 (1993) 699-702 North-Holland
Linear and non-linear optical properties of surfaces and spatially non-local potentials E. Piparo and R. Girlanda Istituto di Struttura della Materia, Facolt~ di Scienze m.fn., Universit~ di Messina, salita sperone 31, C.P. 57, 1-98166 Sant'Agata, Messina, Italy Received 1 September 1992; accepted for publication 19 November 1992 We have developed a theory of the random phase approximation (RPA) optical response of surfaces and interfaces that, in the supercell approximation, takes into account the possible non-locality in the effective potential. One can greatly simplify the theory by decomposing the perturbing electric field into an almost spatially constant external field and an induced z-dependent part; A self-consistent solution of Maxwell equations allows us to express the first and second order in the external field z-dependent densities of polarization by means of "effective" first and second order z-dependent susceptibilities for which approximated expressions are given.