Electron-spin polarization in photoemission from strained GaAs grown on GaAs_1-xP_x

Spin-polarized electron photoemission has been investigated for strained GaAs epitaxially grown on a GaAs_1-xP_x buffer. The lattice-mismatched heterostructure results in a highly strained epitaxial layer and significant enhancement of electron-spin polarization is observed. The effect of epitaxial layer strain is studied for a variety of samples with epitaxial-layer thicknesses varying from 0.1 to 0.3 μm and the phosphorus concentration x varying from 0.21 to 0.28. Electron-spin polarization as high as 90% has been observed. The 0.3-μm-thick sample, well in excess of theoretical estimates for the critical thickness for pseudomorphic growth, reaches an electron-spin polarization of 80%, demonstrating a significant persistence of lattice strain.