Photoinduced and thermal stress in silicon microcantilevers

Abstract

The photogeneration of free charge carriers in a semiconductor gives rise to mechanical strain. We measured the deflection of silicon microcantilevers resulting from photoinduced stress. The excess charge carriers responsible for the photoinduced stress, were produced via photon irradiation from a diode laser with wavelength λ=780 nm. For Si microcantilevers, the photoinduced stress is of opposite direction and about four times larger than the stress resulting from only thermal excitation. In this letter we report on our study of the photoinduced stress in silicon microcantilevers and discuss their temporal and photometric response.

Novel uncooled infrared detectors

“…These detectors have slow response times in comparison with photon detectors. However, the micromechanical structures can be also used as photon detectors with faster response times and higher performance than that of micromechanical detectors [43][44][45][46][47]. The absorption of photons by the solid results in tempe− rature changes and expansion, which in turn gives rise to acoustic waves at frequencies corresponding to the ampli− tude modulation of the incident photon radiation.…”

“…Between them, the most important are bimaterial microcantilevers that mechanically respond to the absorp− tion of the radiation. These sensing structures were origi− nally invented at the Oak National Laboratory (ORNL) in the mid 1990's [11][12][13][14][15], and subsequently developed by ONRL [16][17][18][19][20], the Sarnoff Corporation [21,22], Sarcon Microsystems [23][24][25] and other for imaging [26][27][28][29][30][31][32][33] and photo spectroscopic applications [34,35].…”

“…In dependence on readout techniques, the novel uncooled detectors can be devoted on: [13,15,17,19,20,[26][27][28][30][31][32][33], l piezoresistive [11,12], and l electron tunnelling [8]. …”

Optically induced forces in scanning probe microscopy

“…In this study, the probe was excited below the bandgap for silicon nitride, thus only thermal effects result. If the cantilever is instead excited above the bandgap, the radiation induced mechanical stress is dominated by photoinduced stress [39].…”

Polarization-dependent photoinduced mechanical deformations in covalent chalcogenide glasses

“…The expansion may be proportional to the number of interference fringes, which is greater when light polarization is perpendicular to a cantilever axis, and accordingly, the perpendicular polarization can provide a greater cantilever deflection. Otherwise, more generally, the guided light may provide greater thermal expansion, electrostriction, 40 and radiation pressure. 41 However, these intrinsically scalar changes cannot explain the contracting bending in Se under exposures to the parallel polarization ͓Fig.…”