Applications of strained layer superlattices

Conference · Sat Mar 31 23:00:00 EST 1990

DOI:https://doi.org/10.1557/PROC-184-177· OSTI ID:6975946

Smith, D L; Laurich, B K ^[1]; Mailhiot, C ^[2]

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1. Los Alamos National Lab., NM (USA)
2. Lawrence Livermore National Lab., CA (USA)

Because of different band-edge lineups, strain conditions, and growth orientations, various strained-layer superlattice (SLS) materials can exhibit qualitatively new physical behavior in their optical properties. We describe two examples of new physical behavior in SLS: strain-generated electric fields in polar growth axis superlattices and strained type 2 superlattices. In SLS, large electric fields can be generated by the piezoelectric effect. The fields are largest for SLS with a (111) growth axis; they vanish for SLS with a (100) growth axis. The strain generated electric fields strongly modify the optical properties of the superlattice. Photogenerated electron-hole pairs screen the fields leading to a large nonlinear optical response. Application of an external electric field leads to a large linear electrooptical response. The absorption edge can be either red or blue shifted. Optical studies of (100), (111), and (211) oriented GaInAs/GaAs superlattices confirm the existence of the strain-generated electric fields. Small band gap semiconductors are useful for making intrinsic long wavelength infrared detectors. Arbitrarily small band gaps can be reached in the type 2 superlattice InAs/GaSb. However, for band gaps less than 0.1 eV, the layer thicknesses are large and the overlap of electron and hole wavefunctions are small. Thus, the absorption coefficient is too small for useful infrared (IR) detection. Including In in the GaSb introduces strain in he InAs/GaInSb superlattice which shifts the band edges so that small band gaps can be reached in thin layer superlattices. Good absorption at long IR wavelengths is thus achieved. 22 refs., 9 figs.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• Sponsoring Organization: DOE/DP
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6975946
• Report Number(s): UCRL-102758; CONF-900466--42; ON: DE90011204
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ANTIMONIDES
ANTIMONY COMPOUNDS
ARSENIC COMPOUNDS
ARSENIDES
ELECTRIC FIELDS
GALLIUM ANTIMONIDES
GALLIUM ARSENIDES
GALLIUM COMPOUNDS
INDIUM ARSENIDES
INDIUM COMPOUNDS
MATERIALS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PNICTIDES
SEMICONDUCTOR MATERIALS
STRAINS
SUPERLATTICES