Electron cyclotron plasma etching damage investigated by InGaAs/GaAs quantum well photoluminescence

Photoluminescence (PL) was used to study the damage of (100) GaAs surfaces exposed to BCl3/Ar plasma generated by an electron cyclotron resonance system. With PL measurement of strained InGaAs/GaAs quantum wells within the etched top GaAs layer, our analysis shows that this technique assesses damages to the structure not detected by atomic force microscopy and photoreflectance. A transport model is used to show a 100 times reduction in the Debye length for a 100 nm layer underneath the etching surface. (c) 2006 American Vacuum Society.246SI2726273

Laser reflectometry in situ monitoring structural and growth effects on the electron cyclotron resonance etching of In0.49Ga0.51P layers in Al-free laser structures

Electron cyclotron resonance (ECR) plasma etching of p- and n-In0.49Ga0.51P layers in Al-free laser structures is studied based on BCl3/N-2 gas mixture. Laser reflectometry is used for the in situ etching analysis. Strong etching rate discrepancies are found for the same material whether inserted in multilayer laser structures or in single calibration layers. Strong etching dependence with growth conditions and beryllium concentration is found. Great reduction in etching rate is observed near p(++)GaAs/p(++)In(0.49)Ga(0.51)P interfaces depending on growth conditions. These results are explained by a 200 Angstrom beryllium diffusion in the In0.49Ga0.51P material with subsequent formation of Be3P2 clusters in p-In0.49Ga0.51P during growth. (C) 2001 American Vacuum Society.19119219

Enhanced side-mode suppression in chaotic stadium microcavity lasers

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)We report an enhanced side-mode suppression in Bunimovich stadium lasers with strained InGaAs/InGaP quantum well (QW) active regions. This is realized with spatially selective carrier injection along a particular periodic orbit of the stadium. The selectivity is achieved using He(+3) ion implantation. Up to 21 dB enhancement in side-mode suppression is observed for a 40x20 mu m(2) stadium with interband transition between the first excited quantum well level. The improvement in side-mode suppression is apparently a consequence of coherent beating between orbits leading to a Vernier effect. A simple model corroborate with this hypothesis.1056Centro de Pesquisa em Optica e Fotonica (CePOF)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Fabrication and characterization of Ge nanocrystalline growth by ion implantation in SiO2 matrix

Ge nanocrystallites (Ge-nc) have been formed by ion implantation of Ge+74 into SiO2 matrix, thermally grown on p-type Si substrates. The Ge-nc are examined by Raman spectroscopy, photoluminescence (PL) and Fourier transform infrared spectroscopy (FTIR). The samples were prepared with various implantation doses [0.5; 0.8; 1; 2; 3; 4] x 10(16) cm(-2) with 250 keV energy. After implantation, the samples were annealed at 1,000 degrees C in forming gas atmosphere for 1 h. Raman intensity variation with implantation doses is observed, particularly for the peak near 304 cm(-1). It was found that the sample implanted with a doses of 2 x 10(16) cm(-2) shows maximum photoluminescence intensity at about 3.2 eV. FTIR analysis shows that the SiO2 film moved off stoichiometry due to Ge+74 ion implantation, and Ge oxides are formed in it. This result is shown as a reduction of GeOx at exactly the doses corresponding to the maximum blue-violet PL emission and the largest Raman emission at 304 cm(-1). This intensity reduction can be attributed to a larger portion of broken Ge-O bonds enabling a greater number of Ge atoms to participate in the cluster formation and at the same time increasing the oxygen vacancies. This idea would explain why the FTIR peak decreases at the same implantation doses where the PL intensity increases.42187757776