Photoinduced Anisotropic Deformation in As₂S₃ Glass

Abstract

Silicon nanowires with programmable conductivity which utilized sensitivity of conductance to surface charging have been investigated in terms of complementary operation of p-and n-type devices. The device fabricated from a silicon-on-insulator (SOI) wafer consists of a nanowire (width % 30 nm) and side gates for control of surface charging onto the nanowire. The wire current clearly exhibited hysteresis by sweeping the side gate voltage at a constant rate. The transistor characteristics obtained using the SOI substrate as a back gate also exhibited programmable threshold voltage by applying a pulse bias to the side gate. Surface potential imaging of the nanowire by means of scanning Maxwell-stress microscopy (SMM) has been carried out for correlating the programmability to surface charging. The SMM images clearly explained the origin of the programmability and the complementary operation of the p-and n-type nanowires.

Polarization-dependent photoinduced mechanical deformations in covalent chalcogenide glasses

“…3,5,27,28 The expansion shape is unchanged upon prolonged exposures up to 10 min, being consistent with the previous observation for thick As 2 S 3 films of 2r Շ⌬L. 25 This isotropic expansion may have a common origin to that of relief fringes produced holographically in Se films. 29 On the other hand, when 2r Ն L as in ͑b͒, the anisotropic M-shaped deformation becomes prominent.…”

“…2,8 Photoinduced anisotropic deformations were investigated following the same procedure as that employed previously. 25 In short, the chalcogenide film was irradiated by the laser beam, which was focused to 5-10 m in spot diameter, and then, irradiated areas were imaged using an atomic force microscope ͑AFM͒. In addition, growing dynamics of deformations were inspected, in situ, through transmitted light patterns, which were monitored using a charge coupled device ͑Ophir, BeamStar FX50͒, the method previously being employed for an investigation of optical damages.…”

“…29 On the other hand, when 2r Ն L as in ͑b͒, the anisotropic M-shaped deformation becomes prominent. 25 The central valley and the peripheral peaks are lower and higher by 120 nm and ϳ50 nm than the original film surface, i.e., a peakto-valley difference h being ϳ170 nm. In this case, following the previous study, 25 we expect that an isotropic expansion occurs in advance to this anisotropic deformation.…”

“…In the previous studies, 16,22,23,25 As 2 S 3 films were deposited onto microscope slides, which were exposed to focused linearly polarized laser beams. It was demonstrated that an isotropic expansion appears at first, which gradually transforms to an anisotropic M-shaped deformation with exposure time.…”

“…2 Actually, photodarkening in Se can be detected only at low temperatures. 24 In the present study, therefore, following a previous work on microscopic mechanisms of the photoinduced deformation in As 2 S 3 , 25 we will investigate these problems for these elemental and stoichiometric materials. The OM effect will be measured in somewhat different ways from those employed previously.…”