Properties of the strain-confined electron-hole liquid in Ge

Journal Article · Tue Aug 01 04:00:00 EDT 1978 · Phys. Rev., B; (United States)

DOI:https://doi.org/10.1103/PhysRevB.18.1479· OSTI ID:6686895

Wolfe, J P; Markiewicz, R S; Kelso, S M; Furneaux, J E; Jeffries, C D

A large volume of electron-hole liquid is formed by optically exciting a suitably stressed crystal of Ge. A contact stress produces a maximum shear region inside the crystal which acts as an attractive potential well for photoexcited carriers. Properties of the electron-hole liquid confined to this strain well are determined from spectral and spatial measurements of the recombination luminescence under wide variations in stress, temperature, and excitation level. Both electron-hole liquid and free-exciton phases are observed near 4 K, confirming the interpretation of a first-order liquid-gas phase transition and giving the exciton condensation energy phi approx. = 1 meV. The liquid pair density at intermediate < 111 > stress is determined to be (0.50 +- 0.05) x 10/sup 17/ cm/sup -3/ from a luminescence line-shape analysis which takes into account the reduced electron band degeneracy and the strain-dependent hole mass. Magneto-oscillations in the luminesence intensity are observed which yield a similar density. A tenfold enhancement of the liquid lifetime is observed for stresses above 5 kgf/mm/sup 2/ and 1.8 < or = T < or = 4.2 K, consistent with the reduced pair density and inhibited liquid evaporation in the strain well. Compression of the liquid at high excitation level is reflected in the line-shape, lifetime, and spatial imaging measurements. Time-resolved imaging of the liquid luminescence provides a striking contrast between the strain-confined liquid and the usual cloud of droplets in unstressed Ge.

• Research Organization: Physics Department, University of California, Berkeley, California 94720
• OSTI ID: 6686895
• Journal Information: Phys. Rev., B; (United States), Journal Name: Phys. Rev., B; (United States) Vol. 18:3; ISSN PLRBA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals &amp; Alloys-- Physical Properties
ELEMENTS
EXCITONS
GERMANIUM
LUMINESCENCE
METALS
OPTICAL PROPERTIES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
QUASI PARTICLES
STRESSES