E. Rodriguez Messmer

Semi-insulating epitaxial layers for optoelectronic devices

Semi-insulating epitaxial layers of InP:Fe, GaAs:Fe and GaInP:Fe have been grown. To avoid the often observed inter-diffusion between Fe and Zn, two remedies are proposed using InP:Fe/InP:Zn as an example. One is co-doping InP with sulphur and iron and the other is to use ruthenium instead of iron. In situ mesa etching can also hinder side wall stimulated diffusion. Epitaxial lateral overgrowth studies of InP on a masked surface indicate promising feasibility of integrating SI InP on silicon. InP:Fe and GaInP:Fe/GaAs are found to be useful in the buried heterostructure laser fabrication. Buried in-plane lasers have shown very good thermal and high modulation properties. Buried vertical cavity surface emitting lasers can be pumped up to 97/spl deg/C under continuous operation.

Temporally resolved regrowth of InP

Temporally resolved regrowth of InP around reactive ion etched striped mesas without mask is reported. The regrowth was carried out at the growth temperatures of 600, 650, 685 and 700°C in a near equilibrium process, Hydride vapour phase epitaxy (HVPE). The mesa orientations considered were [110] and [110]. The regrowth profiles, initial lateral growth and evolution of certain crystallographic planes are analysed. The regrowth profiles and initial lateral growth rates are dependent on temperature and mesa orientation. The differences are explained by invoking the bonding configurations existing on the mesa walls under the epitaxial growth conditions of excess phosphorus pressure. The facility of lateral growth especially in the [110] mesa case is explained by a more favourable net reduction of dangling bonds. The emerging crystallographic planes are identified as hhl. Initially the planes with lh ≤ 3 are formed but progress towards lh ≥ 3. The implication of a very high lateral growth rate in utilising regrowth for device fabrication is also mentioned.

Topography dependent doping distribution in selectively regrown InP studied by scanning capacitance microscopy

We have used scanning capacitance microscopy (SCM) to study the dopant distribution in regrown InP with high sensitivity and spatial resolution. Sulfur or iron doped InP was selectively regrown around n-doped InP mesas using hydride vapor phase epitaxy, and the resulting structure was imaged in cross section by SCM. For calibration purposes, reference layers with known doping levels were grown directly on top of the region of interest. Dramatic variations in the carrier concentration around the mesa, as well as pronounced differences in the behavior of S and Fe are observed. We correlate these findings to the growth and doping incorporation mechanisms.

Temporally resolved selective area growth of InP in the openings off-oriented from 110 direction

Temporally resolved selective area growth of InP on patterned substrates with openings off-oriented from [110] direction was studied by low pressure hydride vapour phase epitaxy system. Lateral ove ...

Morphological modifications during selective growth of InP around cylindrical and parallelepiped mesas

Abstract Morphological modifications during selective epitaxy of InP by hybride vapour phase epitaxy around reactive ion etched stripe mesas as in the case of edge emitting lasers were studied by growth of alternating layers of InP and InP:S. The growth profiles were analysed and compared with the selective growth behaviour around reactive ion etched cylindrical and parallelepiped mesas as in the vertical cavity surface emitting lasers. The very initial growth pattern is found to be responsible for the emerging features. The growth along the [110] direction is faster than that along its orthogonal [ 1 10] direction, providing a better planarization along the former. Earlier planarization however can cause mask encroachment, especially in the case of cylindrical mesas, but can be suppressed by using wet etched mesas.

Selective growth of InP on focused-ion-beam-modified GaAs surface by hydride vapor phase epitaxy

The growth of InP islands on a planar focused-ion-beam (FIB)-modified (001) GaAs substrate was investigated in a hydride vapor phase epitaxy system. InP grew selectively on the FIB-implanted lines, forming continuous stripes, whereas isolated islands were observed outside the implanted area. The impact of the III/V ratio, crystallographic orientation of implanted lines, and implantation dose was explored. The choice of suitable growth conditions makes it possible to obtain continuous InP wires aligned in all possible directions. The results of this work could be used for the fabrication of future optoelectronic integrated circuits, which would include nanoscale structures, e.g., quantum-wire optical devices with GaAs electronic circuits.

Maskless selective growth of InGaAs/InP quantum wires on (100) GaAs

A new fabrication process to create InGaAs/InP quantum wires on (100) GaAs substrates is demonstrated. The process is based on the selectivity of the growth of InP on lines created by focused ion beam bombardment, together with the selectivity of the growth of InGaAs on the InP wires. Intense photoluminescene is observed from the wires and the emission shows clear polarization parallel and perpendicular to the wires. Cathodoluminescene images confirm that the luminescence originates from the wires.

GaAs/AlGaAs buried heterostructure laser by wet etching and semi-insulating GaInP : Fe regrowth

Selective regrowth of semi-insulating Ga0.51In0.49P:Fe (SI-GaInP:Fe) by hydride vapor-phase epitaxy around Al-containing wet etched laser mesas is used for the first time to fabricate a GaAs/AlGaAs buried heterostructure laser emitting at 808 nm. The reverse and forward current-voltage characteristics measured at different temperatures up to 80 degrees C indicate no serious leakage current problems. The performance of the laser shows that the SI-GaInP: Fe burying layer fulfills its function as a current and optical confinement layer. The fabrication procedure and the laser characteristics are presented.

Epitaxially regrown GaAs/AlGaAs laser mesas with semi-insulating GaInP: Fe and GaAs: Fe

Selective regrowth of semi-insulating iron-doped Ga0.51In0.49P (SI-GaInP:Fe) and SI-GaAs:Fe around GaAs/AlGaAs mesas by hydride vapor phase epitaxy (HVPE) has been achieved. A HCl based in-situ cleaning procedure has been used to remove aluminum oxide from the etched walls of the mesas. Regrowth conducted without proper cleaning results in an irregular interface with voids. Regrowth morphology aspects are also presented. Our cleaning and regrowth methods have been used for fabricating GaAs/AlGaAs buried heterostructure in-plane lasers and vertical-cavity surface-emitting lasers.

Temporally resolved selective regrowth of InP around [110] and [1¯10] mesas

Temporally resolved selective regrowth of InP around reactive ion etched [110] and [-110] directional mesas is studied by hydride vapor phase epitaxy at the growth temperatures of 600, 650, 685, and 700°C. The regrowth profiles are strikingly different depending upon the mesa orientation. The results are interpreted by invoking the difference in the bonding configurations of these mesas as well as the growth facility in a direction leading to the largest reduction of dangling bonds under the growth conditions. Various emerging planes during regrowth are identified and arehhl planes with initial values of 1/h ≤ 3 but ≥ 3 as the planarization is approached. Initial lateral growth defined as the growth away from the mesa at half of its height in the very first minute is a decreasing function of temperature when plotted as Arrhenius curves. Such a behavior is attributed to the exothermicity of the reaction and to an enhanced pyrolysis of PH3 to P2. The lateral growth rate is much larger than that on the planar substrate. This should be taken into account when regrowth of a doped layer (e.g. InP:Fe or InP:Zn) is carried out to fabricate a buried heterostructure device since the dopant concentration can be very much lower than the one optimized on the planar substrates.