Abstract:
The secondary ion mass spectrometry and capacitance–voltage measurements have been used to study the mechanism of formation of the near-surface layer with a low concentration of uncompensated donors in $n$-GaP grown by vapor-phase epitaxy and subjected to heat treatment at different pressures of phosphorus vapors. The dependence of the thickness of the mentioned layer on the pressure of phosphorus vapors has a minimum at a pressure of (1.5 $\pm$ 0.5) $\times$ 10$^3$ Pa. It is shown that at vapor pressures above the mentioned value, the interstitial P, which forms a deep electron trap, is a suitable candidate for the role of compensating acceptor. At low pressures, the probable compensating center is the P vacancy giving rise to a deep level with the energy $E_c$–(0.21 $\pm$ 0.01) eV. At 700$^\circ$C, the effective diffusivity of interstitial P is $\sim$ (3 $\pm$ 1) $\cdot$ 10$^{-15}$ cm$^2$/s, while that of the P vacancy is $\approx$ (3 $\pm$ 1)
$\times$ 10$^{-14}$ cm$^2$/s.
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