Enhanced light absorption of solar cells and photodetectors by
diffraction is described. Triangular, rectangular, and blazed subwavelength periodic structures are shown to improve performance of solar cells.
Surface reflection can be tailored for either
broadband, or narrow-band
spectral absorption.
Enhanced absorption is achieved by efficient
optical coupling into obliquely propagating transmitted
diffraction orders. Subwavelength one-dimensional structures are designed for polarization-dependent,
wavelength-selective absorption in solar cells and photodetectors, while two-dimensional structures are designed for polarization-independent,
wavelength-selective absorption therein. Suitable one and two-dimensional subwavelength periodic structures can also be designed for
broadband spectral absorption in solar cells and photodetectors. If
reactive ion etching (RIE) processes are used to form the
grating, RIE-induced surface damage in subwavelength structures can be repaired by forming junctions using
ion implantation methods. RIE-induced surface damage can also be removed by post RIE wet-chemical
etching treatments.