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HL: Halbleiterphysik

HL 38: Poster III: Transporteigenschaften (1-14), Optische Eigenschaften (15-31), Grenz-/Oberfl
ächen (32-44), Heterostrukturen (45-57), Bauelemente (58-67), Gitterdynamik (68-69), Diamant (70), Raster-Tunnel-Mikroskopie (71)

HL 38.66: Poster

Donnerstag, 30. März 2000, 14:00–19:00, B

Imaging of submicrometer heat spots and subsurface thermal barriers by optically and electrically modulated photothermal microscopy — •D. Dietzel¹, F. Niebiesch¹, B.K. Bein¹, J. Pelzl¹, A.D. Wieck², C. Crell³, and H. Röcken³ — ¹Experimentalphysik III, Festkörperspektroskopie, Ruhr-Universität Bochum — ²Experimentalphysik VI, Angewandte Festkörperphysik, Ruhr-Universität Bochum — ³Experimentalphysik III, Ruhr-Universität Bochum

The heat spot and the surface and subsurface thermal barriers of

mesa devices have been investigated by means of a photothermal

microscope. The photothermal microscope built by our group offers

a lateral resolution of about 5 microns and relies on the optical

reflection of a He-Ne-laser probe beam by the sample which is

heated by means of a periodically modulated Ar-ion laser.

Subsurface insulating lines which had been generated by focussed

ion beams became visible when in addition a dc voltage was

applied. The inverse OBIC-effect increased linearly with the

applied voltage but did not change markedly with the modulation

frequency of the pump laser varied between 10kHz and 1MHz. The

contrast could be enhanced when the voltage was modulated and

the signal was recorded at multiples of the modulation

frequencies. The observations are explained on the basis of

changes of the reflectance due to induced charge carriers and

temperature effects.

(Work performed in the frame of the GRK 384)