Static and high-frequency electric fields in silicon MOS and MS structures probed by optical second-harmonic generation

Abstract

We present a comprehensive analysis of the effects of static and high-frequency electric fields in silicon metal-oxide-semiconductor ͑MOS͒ and metal-semiconductor ͑MS͒ structures on optical second-harmonic generation ͑SHG͒. First, a general Green's function formalism developed by Sipe ͓J. Opt. Soc. Am. B 4, 481 ͑1987͔͒ is applied to determine the voltage dependence of the SHG response from planar MOS structures. This approach takes directly into account the spatial distribution of the dc-electric-field across the silicon spacecharge region. Predictions of the theory are in good agreement with experimental results of the SHG bias dependence from MS and MOS structures. Furthermore, the azimuthal SHG anisotropy from Si͑111͒ MOS and Si͑001͒ MS interfaces is determined in the presence of a reverse bias allowing a clear separation of various anisotropic contributions resulting from inhomogeneous bias fields and anisotropic (2) or (3) tensor elements. Finally, we demonstrate the capability of optical SHG for time-resolved measurements of free-running GHz signals on silicon millimeter-wave devices. Consequences for circuit testing are discussed.

Optical second-harmonic probe for ultra-high frequency on-chip interconnects with benzocyclobutene

“…Ti:sapphire lasers generating 100 fs pulses of about 10 nJ pulse energy, however, were enabled to measure internal electric fields in crystalline silicon via EFISH generation. [16][17][18][19] This technique does not require an external probe. It suffers, however, from a residual invasiveness as long as the laser energy is larger than the Si band gap.…”

“…The data show a parabolic dependence on the voltage with a minimum at Ϫ23.5 V. The shift from the origin is caused by the interference effect between the two SH contributions, which originates from symmetry perturbation at the polymer/ metal interfaces. This effect can be expressed as 19 …”

Optical Second-Harmonic Generation as a Semiconductor Surface and Interface Probe

“…Both MOS and metal±semiconductor (MS) structures have now been studied by a number of groups [39 to 41]. Recently, an extensive study of both static and high frequency electric fields in Si MOS and MS structures has been carried out by Kurz, Lu È pke, and co-workers [42]. Both linear and parabolic bias dependences of the EFISH response were found, with the former case corresponding to a space-charge region (SCR) larger than the SH sampling region, and the latter case corresponding to the opposite situation, or to the screening of the Si SCR by photogenerated free carriers.…”

“…The fs Ti : sapphire laser also allowed timeresolved measurements (see Section 5) of free-running GHz signals on Si millimeterwave devices. This offers a simpler way of testing Si integrated circuit devices, with sampling band widths of up to 100 GHz being possible [42].…”

Boron induced charge traps near the interface of Si/SiO2 probed by second harmonic generation

“…Because SHG signals vanish for inversion symmetric materials such as silicon and also amorphous SiO 2 under the dipole radiation approximation [1][2][3], SHG signals arise primarily from surfaces and interfaces. When there is an electric field present inside these materials, the SHG signal contains an additional bulk x (3) contribution [4][5][6][7][8]. Electric field induced SHG (EFISH) can be described by the following equation [9,10] …”