Articles you may be interested inInvestigation of improved regrown material on InP surfaces etched with methane/hydrogen/argon J.Quantum dots fabricated in InP/InGaAs by free Cl2 gas etching and metalorganic chemical vapor deposition regrowth J.We have investigated the radiation enhanced diffusion of ion defects during reactive ion beam etching of GaAs and InP, using the multiple quantum well ͑MQW͒ probe technique. During low energy ͑sub-keV͒ Ar ϩ ion exposure, illumination with light of energy above the band gap can substantially reduce the photoluminescence efficiency of MQW samples, relative to those which were not laser illuminated; the degradation of luminescence efficiency increases with the intensity of the light. Illumination with light of energy below the band gap produces a slight increase in the damage profiles. The observation of enhanced defect diffusion due to optical radiation in our studies suggests that in ion-assisted etching of semiconductors, the generation of excess electron-hole pairs and their subsequent recombination can play an important role in the propagation of defects into the substrate.

A Cl2 radical beam ion-beam etching (RBIBE) system was used to etch InP-based materials. In InAlAs/InAlGaAs heterostructures, vertical sidewalls, smooth surfaces, and no delineation of the epilayers resulted from etching at elevated temperatures (≳150 °C) and low ion-beam energies (≤300 eV). Rapid etch rates (≳1 μm/min) were also achieved under these conditions. This work demonstrates that reliable anisotropic and angled etching of InP-based III–V compound semiconductors is possible with the RBIBE system.

Channeling of incident ions and radiation-enhanced diffusion of the ion-created defects have been shown to be major components of the ion damage profile. Our earlier results showed a deeper damage profile in InP, compared to GaAs, when subjected to the same ion bombardment conditions. Computer simulations demonstrated that this can partially be attributed to the greater ion channeling range in InP. In this article the role of defect diffusion in InP, through experiments coupled with simulations, is delineated. The multiple quantum well ͑MQW͒ probe technique is used to determine the amount of damage by measuring the change in low temperature photoluminescence of quantum wells before and after argon ion bombardment. A blocking superlattice is added to the MQW heterostructure and is proven effective in preventing damage from propagating into the material below it. By correlating the experimental results with computer modeling, an estimate of the defect diffusion constant is obtained and it is found to be in the range of 4ϫ10 Ϫ15 -1ϫ10 Ϫ14 cm 2 /s. These high values for diffusion are justified with experimental results that illustrate the presence of radiation-enhanced diffusion mechanisms during ion bombardment.

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