Advanced VCSELs Implemented from Thermal Oxidation Isolation

GaAs-based VCSEL's with thermally oxidized AlxGa(1-x)As current apertures have recently been demonstrated that possess record performance benchmarks in terms of low current thresholds and high power conversion efficiency. Work done at ASU and elsewhere has begun to demonstrate the enormous potential of AlxGa(1-x)As-oxide layers in a variety of additional device-related applications. We have demonstrated a technology to monolithically integrate the device components required to fabricate a smart pixel on a GaAs substrate (VCSELs, detectors and transistors) using a buried oxide layer to provide inter-device isolation. The oxide layer simultaneously forms a current aperture in the integrated VCSELs. The thermal oxidation isolation (TOI) integration technology is commercially relevant because it requires a minimal integrated optoelectronic circuits. We propose to improve this technology by focusing our attention on the oxidation process itself. By optimizing the oxidation for the TOI process, it is anticipated that the performance of integrated VCSELs can be made to match that of oxide-apertured discrete devices and the manufacturability of the TOI technology can be enhanced by better control of the critical oxidation step. Our Phase I work will initially address materials issues and process variables of the oxide and will then use those results to fabricate and characterize integrated optoelectronic circuits using the TOI process.