Free-exciton diffusion and decay in zero-stress Ge

Journal Article · Sat Nov 15 04:00:00 EST 1986 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.34.6980· OSTI ID:5040530

Culbertson, J C; Westervelt, R M; Haller, E E

We report the first direct measurement of the free-exciton (FE) diffusivity D/sub x/ in germanium. The evolution in time of spatial profiles of FE luminescence were measured. From these FE density profiles we determined the diffusivity D/sub x/(4.2 K)approx. =300 cm/sup 2/ s/sup -1/ which is limited by phonon scattering, and the surface recombination velocity Sapprox. =3000 cmX sup -1: , and an FE lifetime tau/sub x/approx. =27 ..mu..s for dislocation free Ge and tau/sub x/approx. =12 ..mu..s for dislocated Ge with surface recombination effects on these tau/sub x/ excluded. Evidence is presented which suggests that the FE recombination velocity S at a crystal surface is not sensitive to the detailed character of that surface. It is concluded that previous measurements could have been dramatically affected by the surface recombination of FE, especially those measurements made on crystals whose dimensions are on the order of the FE diffusion length. An FE-phonon scattering time tau/sub p/(4.2 K)approx. =2 x 10/sup -10/ s is deduced from the measured diffusion constant.

• Research Organization: Naval Research Laboratory, Washington, D.C. 20375-5000
• OSTI ID: 5040530
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 34:10; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
DIFFUSION
DISTRIBUTION
ELECTROMAGNETIC RADIATION
ELEMENTS
ERRORS
EXCITONS
GERMANIUM
LASER RADIATION
LUMINESCENCE
METALS
PHOTOLUMINESCENCE
QUASI PARTICLES
RADIATIONS
RECOMBINATION
SPATIAL DISTRIBUTION
SURFACES
ULTRALOW TEMPERATURE