Surface second harmonic generation from Si/SiO/sub 2/ and GaAs using 10-fs pulses

Summary form only given. The surface selectivity of surface second harmonic generation (SSHG) in centrosymmetric materials makes it a very powerful tool for studying surfaces. The Si-SiO/sub 2/ interface is of particular interest because of its critical role in integrated circuits. SSHG has been used to study surface steps, straining of subsurface bonds, and surface roughness. Early experiments using nanosecond pulses were actually limited by the laser-induced damage to the surfaces, which has resulted in the use of ps and 100 fs pulses to obtain good signal to noise with lower average powers (/spl sim/1 W for 100-fs pulses). We show that by using 10-fs pulses the average power can be reduced to <30 mW with acceptable signal to noise. Additionally we can observe resonance behavior by simply spectrally resolving the SSHG signal.