Work Area: Alternative Advanced Semiconductor Materials, Devices and Process Steps
Keywords II-VI semiconductors, blue lasers, MOCVD organometallic precursor materials, laser technology
Start Date: 1 September 92 / Duration: 36 months / Status: running
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Abstract There is a great demand for visible light-emitting semiconductor lasers. III-V materials are not well-suited for short wavelength applications because their band-gap is generally not wide enough. The best potential materials are the wide-gap II-VI compounds (based on ZnSe, ZnTe, ZnS) which are intrinsically better luminescent materials than the III-V materials. The project aims to produce a semiconductor laser device, emitting in the visible range (blue), in which the active structure is based on MOCVD-grown wide-gap II-VI compounds. This involves developing equipment technology and basic work on precursors prior to the growth and subsequent device processing on the epitaxial layers.
The aim of the project is to develop the II-VI MOCVD technology and its applications in the field of blue light emission (Light Emitting and laser diodes):
The consortium plans to develop wide-gap II-VI compounds growth and doping processes using the MOCVD technology, as European MOCVD growth technologies (equipment and precursors) are very competitive and because MOCVD is widely employed in the industry for the production of compound semiconductor devices (mainly III-V transistors, photodetectors and emitters).
The approach is two-fold. Firstly, a conventional laser structure will be made, involving a p-type ZnSe layer. This needs control of p-type doping in ZnSe. Secondly, a superlattice-based junction will be designed using n-type ZnSe and p-type ZnTe which is capable of exhibiting blue light emission.
The growth of wide gap II-VI compounds using novel precursors designed and produced by EPICHEM has been done. It has been demonstrated that extremely high purity materials (ZnSe, ZnTe and ZnS) could be obtained from triethylamine-dimethylzinc.
This work demonstrate that a level of purity similar to III-V precursors can now be achieved with original II-VI precursors. Other new precursors are currently studied. The successfull growth of ZnSe/ZnTe short-period superlattices has been demonstrated by MOCVD using these precursors. This type of structures will be used in the design of modulation doped devices.
A plasma precracking cell for plasma assisted doping has been developed by ASM France.
The technology of optical information storage is limited by the density of information stored by the resolution of a system. This resolution depends both on disc media and technology, and also on the electro-optical reading system (the main element being the wavelength of the semiconductor laser employed). Up to now, only near infrared lasers based on III-V materials (GaAs/GaAlAs) have been employed, but their long wavelength is a limiting factor for the increase of the information density on the disc. The Blue sources using II-VI materials should constitute a major breakthrough in this domain.
Université de Montpellier II - F
GES - UA 357 CNRS
Place Eugene Bataillon
F - 34095 MONTPELLIER
Ecole Polytechnique Fédérale de Lausanne - CH
Thomson-CSF - F
ASM France - F
Epichem Ltd - UK
Dr. O. Briot
tel +33/67 41 06 05
fax +33/67 14 42 40
MTVLE - 6675, August 1994
please address enquiries to the ESPRIT Information Desk
html version of synopsis by Nick Cook