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Metalorganic Chemical Vapour Deposition Laboratory

Associate Professor Ewa M. Goldys

April 2001

Metalorganic Chemical Vapour Deposition (MOCVD) is a technique of synthesis of semiconductor materials based on a chemical reaction of special chemicals called metalorganic precursors in a vapour phase (hence the name). The process is carried out using a commercial MOCVD reactor built by Thomas Swan. The metalorganic precursors are transported into the reactor chamber using hydrogen carrier gas. High temperature in the chamber decomposes the precursors and the liberated atoms recombine forming a semiconducting compound. This takes place on substrates placed on a radiatively heated susceptor resulting in film growth.

Present activities centre around growth, characterisation and device applications of antimonides. This group of semiconductors is characterised by a narrow bandgap with high speed capabilities and applications in infrared electronics. For several years we have been exploring growth of high quality undoped gallium antimonide and have established the optimum growth window and growth protocols. Variations of p-type doping level is achieved by adjustments of growth parameters We have also carried out successful n-type doping of GaSb using trimethylzinc. We continue our work on growth of high electronic quality undoped AlGaSb. Our present interests focus on growth of GaSb quantum dots, where we have achieved the fascinating results described.

The antimonides are set to become the next hot topic in semiconductors (after silicon, GaAs and recently GaN). Their favourable combination of low effective mass and the bandgap corresponding to just below 1.5 micrometers wavelength make GaSb an ideal candidate for high speed light detectors. We currently offer a postgraduate project on light detection using GaSb, which will make use of our p-and n-type doping capabilities. Fabrication of the devices will take place in our fully equipped clean room.

Selected publications arising from this program include

1. A.Subekti, E.M. Goldys, T.L. Tansley,"Characterisation of undoped gallium antimonide grown by metalorganic chemical vapour deposition", J. Phys. Chem. Sol. 61, p. 537-44, (2000).
2. A. Subekti, E.M. Goldys, Melissa J. Paterson, K. Drozdowicz-Tomsia, T.L. Tansley, "Atmospheric Pressure Chemical Vapour Deposition Growth Window for Undoped Gallium Antimonide", Journal of Materials Research, 14, p. 1238-45, (1999).
3. A. Subekti, T.L. Tansley, E.M. Goldys, "Characterisation of microcrystalline GaN Grown on Quartz and on "Tunnelling transport in Al-n-GaSb Schottky diodes", IEEE Transaction on Electron Devices, vol 45 no 10, 2247 (1998).
4. A.H. Ramelan, K. Drozdowicz-Tomsia, E.M. Goldys, T.L. Tansley, "Study of Optical and Electrical Properties of GaSb/AlxGa1-xSb Grown by Metalorganic Chemical Vapour Deposition", accepted in J. Electron. Mat.
5. A. Subekti, E.M. Goldys and T.L. Tansley, ''Growth of Gallium Antimonide (GaSb) by Metalorganic Chemical Vapour Epitaxy'', Conference on Optoelectronic and Microelectronic Materials and Devices, COMMAD96 8-11 Dec. 1996 Canberra, p. 426 (1997).
6. K. Drozdowicz-Tomsia, Agus Subekti, E.M. Goldys and Melissa J. Paterson, "GaSb films and self-assembled islands grown by MOCVD", 16 General Conference of the Condensed Matter Division of the European Physical Society, 28 August - 28 August 1997, Leuven, Belgium.
7. " A.H. Ramelan, K. Drozdowicz-Tomsia, E.M. Goldys, T.L. Tansley, " Study of Optical and Electrical Properties of GaSb/AlxGa1-xSb grown by MOCVD11-th International Semiconducting and Insulating Materials Conference Canberra Australia 3-7 July 2000.
8. A.H. Ramelan, K.S.A. Butcher, E.M. Goldys, T.L. Tansley, Electrical Properties of Te-Doped MOCVD Grown GaSb Schottky Diodes, 2000 Conference on Optoelectronic and Microelectronic Materials and Devices, Melbourne, Australia, 6-8 December 2000