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III-V Materials
Overview of Research
The work on III-V materials can be broken down into three main research themes:
- electrical isolation of III-V semiconductor materials using ion implantation
- SMARTCUT in GaAs
Aims and Objectives
Aims:
- to gain a detailed physical understanding of the electrical isolation
of III-V semiconductor materials using ion implantation.
- to examine the SMARTCUT technique in gallium arsenide.
Objectives:
Electrical Isolation in III-V Materials using ion implantation
- to use the data obtained from fundamental measurements to optimise
present techniques used for isolation.
- to develop technology to enable implant isolation to be expanded to
the fabrication of devices for which no reliable method currently exists.
- to offer any newly developed technology to users of the IBC, including
industry.
SMARTCUT in GaAs
- to understand the mechanisms for the production of blisters in hydrogen
implanted GaAs.
Achievements
Electrical Isolation in III-V Materials using ion implantation:
- shown that 200°C implants of protons in GaAs produce high sheet
resistances (108 ohms/square) with improved thermal stability compared with
room temperature implants.
- developed technology to produce sheet resistances of about 107 ohms/square
for both n-type and p-type InP and InGaAs.
- industry using our improved technology for producing microwave devices/circuits.
- work has been in collaboration with UCL and UMIST and includes the
industrial partners, PRP Optoelectronics, Qinetiq and E2V Technologies.
SMARTCUT in GaAs:
- have produced blisters in GaAs following implantation at 200°C
without subsequent annealing.
- have produced blisters in 300°C implants in GaAs, but only after
annealing.
- have measured damage and hydrogen profiles using RBS and ERD.
- have found that the formation of blisters depends critically on the
substrate temperature and the dose rate.
- collaboration has been established with UCLA and Salford.
Update
This work, which has mostly been supported by an EPSRC funded project, has
continued to make good progress within the last year. Recently we have developed
techniques to produce resistivities of about 107 ohm/square for both n-type
and p-type InP and InGaAs, which is better than has ever been achieved before.
We have studied a wide range of ion species and ion doses as a function of
the implant temperature, the material type and the doping density and have
applied many of our findings to real devices, such as quantum well saturable
absorbers and HBTs. All of our results have been communicated to our industrial
collaborators and many have been published (>30 publications); for further
details see the
project website .
A second small grant was awarded by EPSRC to support additional ion beam
hours required to complete the project. Another small grant application has
been made to support work begun on GaInAsP.
A new topic, SMARTCUT of GaAs has been running for about one year in which
an EPSRC sponsored student is studying the basics of the process. We have
established a collaboration with groups from UCLA and Salford.
Recent Publications (2002 -2004)
For a full list of IBC publications please
click here
.
- S Ahmed, BJ Sealy and RM Gwilliam, Annealing characteristics of the
implant isolated n-type GaAs layers: effects of ion species and implant temperature,
NIM B 206 (2003) 1008-1012.
- P Too, S Ahmed, R Jakiela, A Kozanecki, A Barcz, BJ Sealy and R Gwilliam,
Implant isolation of both n-type InP and InGaAs by iron irradiation: effect
of post annealing temperature, EDMO (2003), IEEE, pp18-23.
- BJ Sealy, Proton isolation revisited, III-Vs Review, 16 (2003) 36-38
- P Too, S Ahmed, R Gwilliam and B J Sealy, "Electrical isolation of
n-type layers by helium implantation at variable substrate temperatures,"
NIM B188 (2002) 205-209.
- S Ahmed, B J Sealy, and R Gwilliam, "Dose dependence of proton-isolated
n-type GaAs layers implanted at room temperature and 200ºC, Elect Letters,
38 (2002) 250-252.
- S Ahmed, R Gwilliam and B J Sealy, "Implant isolation in GaAs device
technology: Effect of substrate temperature" NIM B188 (2002) 196-200.
- P. Too, S. Ahmed, B. J. Sealy, and R. Gwilliam, "Electrical characterization
of Fe-doped semi-insulating InP after helium bombardment at different implant
temperatures," Appl Phys Lett 80 (2002) 3745-3747.
- P Too, S Ahmed, C Jeynes, B J Sealy, and R Gwilliam, "Electrical isolation
of n-type InP using MeV iron implantation at different doses and substrate
temperatures," Elect Lett 38 (2002) 1225-1226.
- S Ahmed, J P Too Heng Kwee, B J Sealy and R M Gwilliam, "Proton implantation
for effective electrical isolation of InP, InGaAs and GaAs: role of variable
doses and implant temperature," Proc. 14th Conf Indium Phosphide and Related
Materials. Piscataway, USA: IEEE, 2002, pp225-228.
- S C Subramaniam, A A Rezazadeh, J P Too Heng Kwee, S Ahmed, B J Sealy
and R M Gwilliam, "Annealing characteristics of He+-ion implant isolation
of InP/InGaAs HBT structures," Proc 14th Conf on Indium Phosphide and Related
Materials. Piscataway, USA: IEEE, 2002, pp205-208.
- Ahmed S, Sealy BJ, Gwilliam RM. Electrical isolation of n-type
GaAs devices by MeV/MeV-like implantation of various ion species. Proceedings
EDMO, London, UK: IEEE, 2002, p18-23.
- Too Heng Kwee JP, Ahmed S, Sealy BJ, Gwilliam RM. Comparison
of two different isolation schemes for n-type InP by helium implantation,
Proceedings EDMO. London, UK: IEEE, 2002, pp160-165.
- Ahmed S, Sealy BJ, Gwilliam RM. Effect of proton implantation
at variable temperatures and doses on the semi-insulating GaAs. NIM
B 206 (2003)1003-1007.
- M Webb, R Gwilliam, C Jeynes, S Donnelly, A Gandy, M-F Beaufort and
BJ Sealy, Investigation into the implant parameters for smartcut in GaAs,
PREP2004 April (2004)
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