SCANNING-TUNNELING-MICROSCOPY STUDY OF INP(001) SURFACES PREPARED BY UHV DECAPPING OF METAL-ORGANIC VAPOR-PHASE-EPITAXY-GROWN SAMPLES

In this study we report on an investigation of the microscopic structu re of InP(001) surfaces grown by metal-organic vapor-phase epitaxy (MO VPE). InP(001) homoepitaxial layers were grown in a MOVPE reactor and capped in situ with a P/As sandwich layer by photodecomposition of the phosphine and arsine precursors in the gas phase. The passivated samp les were transferred through atmosphere into a separate UHV system. Af ter thermal desorption of the capping layers, a clear (2X4) LEED patte rn was achieved. STM images show large, flat surface areas. Images wit h atomic resolution reveal a (2X4) surface structure corresponding to an In-rich surface. The microscopic surface structure is discussed in the light of recently proposed structure models.