Hamburg 2001 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

HL: Halbleiterphysik

HL 30: III-V Halbleiter II

HL 30.1: Vortrag

Donnerstag, 29. März 2001, 10:30–10:45, S16

Interband transitions in (GaP)₁/(InP)_m monolayer superlattice structures grown on (001) InP — •J. Šik¹, M. Schubert¹, T. Hofmann¹, H. Schmidt¹, G. Böhm¹, and V. Gottschalch² — ¹Fakultät für Physik und Geowissenschaften, Inst. für Exp. Physik II, Universität Leipzig, Linnéstraße 5, 04103 Leipzig — ²Fakultät für Chemie und Mineralogie, Halbleiterchemie, Universität Leipzig, Linnéstraße 3, 04103 Leipzig

Spectroscopic ellipsometry (SE) and empirical pseudopotential calculations are used to study the optical properties of tensile strained short-period [001] (GaP)₁/(InP)_m monolayer (ML) superlattices (SL) for m = 5 - 55 and photon energies from 1 to 6 eV deposited on Si-doped (001) InP substrates by MOVPE. Structure, composition, strain and layer thicknesses are determined by HRTEM and HRXRD. Adachi’s critical-point composite model is employed for SE data analysis of the E₀-, E₀+Δ₀-, E₁- and E₁+Δ₁-type transitions of the SL’s. We report a much smaller blue shift of E₀ compared to the respective strained random alloy Ga_xIn_1−xP band gap, where x = 1/(1+m). The observed band-gap dependence on m is in good agreement with our empirical pseudopotential calculations. We estimate the maximum band-gap reduction ΔE_g for CuAu-I-type ordered GaInP₂ with [001] ordering direction. The E₁- and (E₁+Δ₁)-CP dependences can be explained within the classical elasticity theory as sum of the effects of biaxial strain and alloying, as observed in recent piezo-optics experiments on InP [Rönnow et al., Phys. Rev. B 57, 4432 (1998)].