Properties of a-C:H light-blocking layer used for optical isolation of a-Si:C:H photosensor in reflective liquid crystal spatial light modulators

Abstract

Novel employment of the absorbing a-C:H layer for optical isolation of an a-Si:C:H photosensor in the reflective liquid crystal optically addressed spatial light modulators is discussed. The dependences of electrical resistivity ρ, Tauc gap ET and an absorption coefficient α at 633 nm on the deposition rate of the a-C:H films in the interval from 1 to 10 Å s-1 were compared and correlations between these properties were ascertained to match the a-C:H layer with the a-Si:C:H layer electrically. Current-voltage characteristics of ITO/a-C:H and ITO/a-Si:C:H/a-C:H thin-film structures were measured using a mercury droplet contact. Our investigations showed that the absorbing a-C:H layer with α~4×104 cm-1 at λ = 633 nm-1, ρ in the range from 1010 to 1011 Ω cm, and ET in the range from 1.25 up to 1.5 eV can ensure effective optical isolation and be a well matched couple with the a-Si:C:H photoconductor. The photocurrent and dark current I-V characteristics of such ITO/a-Si:C:H/a-C:H thin-film structures were symmetrical. The ratio between photocurrents and dark currents of such structures was governed by the photosensitivity of the a-Si:C:H layer and depended on the electrical resistance of the a-C:H layer.

Amorphous Hydrogenated Carbon Films with Diamond-Like and Polymer-Like Properties

“…The values of ρ and r are plotted in a logarithmic scale. Representative Tauc gap data changed from ∼0.8 up to ∼1.7 eV, and an exponential rise of ρ of five orders of magnitude from ∼10 8 to ∼10 13 Ω cm was observed at the same time in [45] (Figure 10). The atomic structure of the diamond-like can be described as a stressed-bond rigid lattice, in which mixed bonds predominate with local electronic systems of π-bound atoms imbedded in it.…”

Irradiation Effect on Al-Dispersed Amorphous Silicon Thin Films by Femtosecond Laser

“…Amorphous silicon (a-Si) based thin films have been widely used in solar cells [1,2], optical modulators [3,4] and memristors [5,6], etc. However, the a-Si thin film has some serious problems as Steabler-Wronski (S-W) effect [7,8], which makes its performance gradually deteriorating over time.…”