Absorption and Transmission of Macroporous Silicon and Nanowires

Absorption and transmittance of macroporous silicon and nanowires are calculated using the proposed analytical model. The analytical model takes into account the absorption and transmission of the macroporous layer and the monocrystalline substrate. The influence of the pore volume fraction and pore depth on the absorption and transmittance of macroporous silicon is calculated. The macroporous layer and the nanowire layer are considered as an effective medium. The structured surfaces of the macroporous layer are considered as Lambert surfaces. Absorption and transmittance of macroporous silicon and silicon nanowires are calculated according to formulas found analytically. Reflection from the surfaces of macroporous silicon affects the absorption, transmission, and trapping of light by the macroporous silicon. The absorption of macroporous silicon increases with an increase in the volume fraction of pores, due to a decrease in the effective refractive index of the macroporous silicon layer. The absorption of macroporous silicon begins to decrease at high pore volume fraction due to the increase in reflection from the boundary of the layer of macroporous silicon with a monocrystalline substrate. The absorption spectrum of macroporous silicon does not depend on the pore depth when the pore volume fraction is less than 0.25. The transmittance of macroporous silicon increases with an increase in the volume fraction of pores in relation to single crystal silicon. An increase in the thickness of the macroporous silicon and a decrease in the thickness of the monocristalline substrate lead to an increase in the transmittance of macroporous silicon.