Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 32: C/diamond

HL 32.3: Vortrag

Mittwoch, 28. März 2007, 17:00–17:15, H14

Suppressed formation of electron-hole droplets in diamond under strain — •Nobuko Naka, Junko Omachi, and Makoto Kuwata-Gonokami — Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan

Recent advances in growing high-purity single crystal diamonds have led to new opportunities to investigate the optical properties of high-density electron-hole systems created by photo-excitation in diamond. At low temperature, droplets (EHD) of electron-hole pairs in the liquid phase coexist with excitons or plasmas in the gas phase [1,2]. Shimano et al. [2] studied the formation dynamics of the EHD by applying time-resolved luminescence spectroscopy to a type IIa diamond crystal grown by high-temperature, high-pressure synthesis. The luminescence signal originating from EHD has a rise time of 60 ps, while plasma luminescence emerges within the experimental resolution. From temperature dependence measurements, they reported a critical temperature of 165 K for the EHD formation. Although this temperature is much higher than the ones reported for silicon and germanium, EHD in diamond are stabilized due to a delicate balance of the correlation, exchange, kinetic, and excitonic Coulomb energies. We report on suppressed EHD formation in a diamond crystal under strain perturbation.

[1] K. Thonke et al., Diamond Relat. Mater. 9, 428 (2000), N. Teofilov et al., ibid. 12, 636 (2003).

[2] R. Shimano et al., Phys. Rev. Lett. 88, 057404 (2002).