Ultrafast laser-induced structural changes in semiconductors

Conference · Mon Dec 01 04:00:00 EST 1997

OSTI ID:552285

Mazur, E; Glezer, E N; Huang, L; Callan, J P ^[1]

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1. Harvard Univ., Cambridge, MA (United States)

We present experimentally determined values of the dielectric function of GaAs following femtosecond laser excitation. The data at photon energies of 2.2 and 4.4 eV show that the response of the dielectric function to the excitation is dominated by changes in the electronic band structure and not by the optical susceptibility of the excited free carriers. The behavior of the dielectric function indicates a drop in the average bonding-antibonding splitting of GaAs following the excitation, which leads to a collapse of the band gap. The changes in the electronic band structure result from a combination of electronic screening, many-body effects, and structural deformation of the lattice caused by the destabilization of the covalent bonds. Broadband measurement of the dielectric function over the range 1.5-3.5 eV reveals ultrafast laser-induced heating at low fluence, disordering at intermediate fluence, and an ultrafast semiconductor-to-metal transition at high fluence.

• Research Organization: International Society for Optical Engineering, Washington, DC (United States)
• OSTI ID: 552285
• Report Number(s): CONF-961070--Vol.2966; CNN: Contract ONR N00014-89-J-1023
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
66 PHYSICS
DIELECTRIC PROPERTIES
GALLIUM ARSENIDES
LASER-RADIATION HEATING
PHASE TRANSFORMATIONS
SEMICONDUCTOR MATERIALS