Daniele Bertone

Etching of InP-based MQW laser structure in a MOCVD reactor by chlorinated compounds

Four different chlorinated compounds: 2-chloropropane, dichloromethane, chloroform and carbon tetrachloride have been used to etch InGaAsP/InP MQW laser structures partially masked. Etching experim ...

MOCVD regrowth of semi-insulating InP and p-n junction blocking layers around laser active stripes

The deposition of semi-insulating InP and the realization of a p-n junction by pulsed metalorganic epitaxy improves the regrowth adjacent to tall mesa stripes, avoiding a polycrystalline deposit on the SiN x mask and bumps formation near the edges. By this growth technique, three different buried laser were obtained: conventional buried ridge structure BRS, multi-junction planar buried heterostructure MJ-PBH and semi-insulating buried ridge structure SI-BRS. Static and dynamic characteristics show good lateral current blocking properties in SI compared to MJ and conventional BRS structure.

Comparison of optical and electrical modulation bandwidths in three different 1.55-μm InGaAsP buried laser structures

Static and dynamic characteristics of three different laser structures, by using the same active structure, have been investigated: (1) conventional BRS (Buried Ridge Structure), (2) p-n multi-junctions (MJ) blocking layers and (3) Fe-doped semi-insulating (SI) InP blocking layer. Good blocking properties in MJ and SI laser structures have been showed by measuring the DC leakage current and the linearity of the power versus current (P-I) curve, also at high operating temperature; SI laser, respect to BRS and MJ structures, has shown a large reduction in parasitic capacitance and a considerable improvement in modulation bandwidth, limited only by dynamic characteristic of active region.

High reliability, high-yield, high modulation bandwidth, low threshold current 1.55 /spl mu/m MQW laser by new in-situ etching technique

For the first time to our knowledge, an InP based Fabry-Perot MQW semiconductor laser is obtained by using an in-situ etching technique. Good static and dynamic laser characteristics together with high process yield and reliability confirm the validity of this new technological process.

Eaves Structures on (100) InP and InP/InGaAsP/InP Heterostructures

An etching method for eaves structures on (001) InP and InP/InGaAsP/InP double heterostructures is presented. The eaves structures are etched by a combination of reactive ion etching and wet chemical etching with a Si 3 N 4 mask. Using this method the vertical and lateral etched depth have been controlled separately by reactive ion etching and wet chemical etching. The fundamental characteristics of the wet chemical etching on a mesa structure, such as etched profiles and etching rates, are studied using H 3 PO 4 :H 2 O:saturated bromine water, HNO 3 :HBr:H 2 O and HBr:H 2 O:saturated bromine water solutions. Influence of the etched profiles and orientations on metallorganic chemical vapor deposition growth behavior is investigated. Using this method 1.55 μm wavelength high modulation bandwidth semiconductor lasers have been fabricated.

Structural characterization techniques for the analysis of semiconductor strained heterostructures

A combined method for structural characterization of strained epitaxial heterostructures involving different techniques such as Rutherford backscattering spectrometry (RBS), multiple crystal X-ray diffractometry (MCD) and transmission electron microscopy (TEM) is presented. In order to obtain a complete characterization of the analysed structure, three different quantities are measured independently: the epilayer thickness, the density of misfit dislocations which may appear at the interface, and the significant components of the strain tensor, mainly the tetragonal distortion, affecting the epilayer lattice. In this way the thermodynamic state and the mechanisms of plastic deformation of the structures can be fully investigated. In this contribution we present and discuss the experimental results concerning a set of InP/GaAs samples having different layer thicknesses ranging from 5 to 500 nm. The thickness of the samples has been determined by RBS. Measurements of in-plane strain and tetragonal distortion have been performed by MCD and RBS-channelling respectively, finally TEM has been used for determining the defects densities and distribution.

Electron Microscopy and X‐Ray Diffraction Characterization of InP / GaAs Grown by Atomic Layer Epitaxy

Atomic layer epitaxy has been found to be effective in achieving 2-dimensional growth of highly mismatched InP/GaAs heterostructures from the initial stages. The structural characterization of the layers has been carried out b conventional and high resolution transmission electron microscopy and high resolution x-ray diffractometry. 60 o type misfit dislocations have been observed at the heterointerface in all the structures investigated. As the layer thickness increases, neighboring 60 o dislocations can react to form 90 o edge type dislocations. Planar defects extending into the layers along the (111) planes have also been observed. Finally, the elastic strain relaxation has been correlated with the nature and density of the observed crystal defects

Transition from island to continuous InP layer growth on (001) GaAs by MOCVD

Abstract Low pressure metal-organic chemical vapour deposition grown InP/GaAs layers were analysed using scanning and transmission electron microscopy and Rutherford backscattering spectroscopy to characterize the evolution of the InP layer morphology from the initial stages of the growth up to the complete substrate coverage. Up to nominal thicknesses of about 100–150 mm, an appreciable fraction of the GaAs substrate is not covered by InP. For higher thicknesses, a sudden transition to an enhanced lateral growth leading to island coalescence was observed. Finally, a third growth stage leads to the complete filling of the valleys, leading to continuous layers. The results are discussed in terms of the phenomenological models proposed in the literature.