The main objectives of HISEL are the design, fabrication and characterization of electronic and optoelectronic devices for high speed processing and communications. These devices are based on III-V compound semiconductors, and present research is focused on GaAs/GaAlAs and InGaAs/AlInAs/InP alloy systems including non standard (111) orientation. Activity in the GaN/AlN system started in late 1995.
HISEL runs a Riber 2300 MBE system (solid sources) since early 1990. In late 1995 a MECA 2000 MBE system using a RF plasma source was devoted to the growth of AlInGaN alloys. Other technological facilities are part of a Joint Semiconductor Laboratory, where LPE, VPE, SEM, SIMS, photolithography, UHV metallization, ion implantation, RTA, LPCVD, diffusion, annealing, and sample preparation techniques are available. Facilities for electrical and optical characterization of heterostructures and devices comprise automated DC and low frequency measurements (Hall, I-V, Resonant Tunneling, C-V, 1/f noise, transistor parameters), capacitance and current DLTS, hydrostatic pressure cells, photoluminescence and Raman spectroscopy and time domain photoresponse systems. Access to the microwave characterization facilities allows device and noise measurements from DC to 30 GHz.
Simulation activities are focused on strained InGaAs/GaAs structures, grown on both (100) and (111) orientations. A self consistent Poisson-Schroëdinger solver that includes valence band model, strain effects, piezoelectric fields, optical response, etc., has been developed regarding PMHEMT and piezoelectric device simulation and optical assessment. Channel width effects, alloy scattering and interface roughness are being modeled in relation to channel transport properties in HEMT's. Resonant tunneling devices (RTD's) are also being modeled using a transfer matrix approach. Both (100) and (111) orientations are also considered.
HISEL has been a partner in ESPRIT 5003 Planet project, and it has been the Coordinator of ESPRIT Basic Action 3168 on DX Centers. HISEL has been involved in ESPRIT Project BLES (buffer layer engineering in semiconductors) and in ESPRIT Basic Working Group Eltrasin, dealing with transport properties in III-V devices. A new ESPRIT Project on blue lasers based on GaN has just started (Project LTR LAQUANI, 20968). Integrated Action with IFA-Freiburg, Sheffield and Lisbon were recently finished, and a new cooperation with the University of Cardiff has started. Under the Human Capital and Mobility Program, HISEL is member of a Network on Strained III-V Structures (SQUAD). NATO CRG's for cooperation with the Universities of Cornell, Iowa and Colorado have been granted. At the national level, research programs related to photodetectors, photoreceivers and tunable lasers for optical fiber communications were carried out in cooperation with Telefónica I+D and under the support of CICYT.
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