Analysis of surface photoabsorption spectra of (001) InP surfaces

We present an in situ surface photoabsorption (SPA) study on surface struct ures of (001) InP surfaces. Conventional subtraction spectra of SPA on (001 ) InP showed two peaks at 430 nm and 600 nm, which we assigned as P dimer a nd In dimer peaks, respectively. By modifying the conventional subtraction equation to separate contributions from In- and P-stabilized surfaces, we c ould observe another structure at 400 nm which we interpret as related to I n-stabilized surface, showing possibility of complementary role of this mod ified equation. We also observed evolution of surface states from P- to In- stabilized surfaces at 600 degrees C by the change of PH3 partial pressure.