MODELING OF LOW-POWER CW LASER-BEAM HEATING-EFFECTS ON A GAAS SUBSTRATE

Citation
D. Abbott et al., MODELING OF LOW-POWER CW LASER-BEAM HEATING-EFFECTS ON A GAAS SUBSTRATE, Solid-state electronics, 42(5), 1998, pp. 809-816
Citations number
9
Categorie Soggetti
Engineering, Eletrical & Electronic","Physics, Applied","Physics, Condensed Matter
Journal title
ISSN journal
00381101
Volume
42
Issue
5
Year of publication
1998
Pages
809 - 816
Database
ISI
SICI code
0038-1101(1998)42:5<809:MOLCLH>2.0.ZU;2-9
Abstract
A scanning laser beam is a common method used to characterise the opti cal response of GaAs devices. Laser heating of the substrate, however, can alter the local temperature and hence spuriously shift the values of the electrical parameters of interest. In order to assess the magn itude of this problem, we have solved the steady-state heat equation, with the aid of Kirchhoffs transformation. We show for practical dimen sions, that correct temperature prediction does not depend on the late ral boundary conditions. We find that the variable that is most tightl y coupled to any temperature increase is the power of the laser beam. Usual approximations for the power dissipation density, in the substra te, were found inadequate. A more complete model that considers power dissipation as an exponential function of substrate depth was found to be necessary. We conclude that for low power applications, i.e. using lasers less than 1 mW, heating effects can be considered negligible. For higher powers our results offer worst-case predictions of the loca l substrate temperature rise. Published by Elsevier Science Ltd. All r ights reserved.