Free-form ILT has the best lithography quality but suffers long runtime and large file sizes. The shortcomings can be mitigated by using spline-polygon curvilinear mask. Further more curvilinear OPC can be used to drive down the EPE, further improving the runtime and correction quality
As semiconductor features shrink in dimension and pitch, the excessive control of critical-dimension uniformity (CDU) and pattern fidelity is essential for mask manufacturing using electron-beam lithography. Requirements of the electronbeam shot quality affected by shot unsteadiness become more important than before for the advanced mask patterning. Imperfect electron optical system, an inaccurate beam deflector, and imprecise mask stage control are mainly related to the shot unsteadiness including positioning and dose perturbations. This work extensively investigates impacts of variable shaped beam dose and positioning perturbations on local CDU using Monte Carlo simulation for various mask contrast enhancement approaches. In addition, the relationship between the mask lithographic performance and the shot count number correlated with mask writing time is intensively studied.
KEYWORDS: Scattering, Air contamination, Mie scattering, Light scattering, Thin film solar cells, Thin films, Solar cells, Absorption, Particles, Glasses
Light trapping techniques such as textured interfaces and highly reflective back contacts are important to thin-film solar
cells. Scattering at rough interfaces inside a solar cell leads to enhanced absorption due to an increased optical path
length in the active layers, which is generally characterized by a haze ratio. In this work, we demonstrate the measured
haze characteristics of indium tin oxide nano-whiskers deposited on an ITO-coated glass substrate. A theoretical model
based on a modified Mie theory is also employed to analyze the scattering effects of nano-whiskers. Instead of spherical
model, a cylindrical condition is imposed to better fit the shapes of the whiskers. The calculated haze-ratio of an ITO
whisker layer matches the measurement closely.
In this work, we demonstrate a thorough device design, fabrication, characterization, and analysis of biomimetic
antireflective structures implemented on a Ga0.5In0.5P/GaAs/Ge triple-junction solar cell. The sub-wavelength structures
are fabricated on a silicon nitride passivation layer using polystyrene nanosphere lithography followed by anisotropic
etching. The fabricated structures enhance optical transmission in the ultraviolet wavelength range, compared to a
conventional single-layer antireflective coating (ARC). The transmission improvement contributes to the enhanced
photocurrent, which is also verified by the external quantum efficiency characterization of fabricated solar cells. Under
one-sun illumination, the short-circuit current of a cell with a biomimetic structures is enhanced by 24.1% and 2.2% due
to much improved optical transmission and current matching, compared to cells without an ARC and with a conventional
ARC, respectively. Further optimizations of the biomimetic structures including the periodicity and etching depth are
conducted by performing comprehensive calculations based on a rigorous couple-wave analysis method.
In this work, we present a solution that employs combined micro- and nano-scale surface textures to increase light
harvesting in the near infrared for crystalline silicon photovoltaics, and discuss the associated antireflection and
scattering mechanisms. The combined surface textures are achieved by uniformly depositing a layer of indium-tin-oxide
nanowhiskers on passivated, micro-grooved silicon solar cells using electron-beam evaporation. The nanowhiskers
facilitate optical transmission in the near-infrared, which is optically equivalent to a stack of two dielectric thin-films
with step- and graded- refractive index profiles. The ITO nanowhiskers provide broadband anti-reflective properties
(R<5%) in the wavelength range of 350-1100nm. In comparison with conventional Si solar cell, the combined surface
texture solar cell shows higher external quantum efficiency (EQE) in the range of 700-1100nm. Moreover, the ITO nano-whisker
coating Si solar cell shows a high total efficiency increase of 1.1% (from 16.08% to17.18%). Furthermore, the
nano-whiskers also provide strong forward scattering for ultraviolet and visible light, favorable in thin-wafer silicon
photovoltaics to increase the optical absorption path.
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