Chemical-bonding structure of InP surface in MOVPE studied by surface photo-absorption

Using surface photo-absorption spectra, we established a phase diagram of the surface chemical-bonding structure for the P-stabilized surface in InP metalorganic vapor phase epitaxy as a function of substrate temperature and PH3 partial pressure. At 550 degrees C and PH3 partial pressures of 10 and 30 Pa, the surface is (2 x 4)-like consisting of P dimers having a bond axis parallel to [<(1)over bar10>]. As the substrate temperature decreases and the PH3 partial pressure increases, amorphous P species start to adsorb excessively on (2 x 4)-like P dimer surface. A c(4 x 4)-like surface was not observed. From InP growth experiments for each P surface phase, we found that, to obtain high-quality InP epitaxial layers, excess P adsorption should be suppressed by minimizing the formation of native defects.