Surface-relief diffractive microstructures for improving efficiency fastening response of photodetectors

The approach provided by B. D. Clymer [in "Surface-relief grating structures for efficient high bandwidth integrated photodetectors for optical interconnections in silicon VLSI", Appl. Opt. 28, 5374 (1989)] is revisited in order to consider issues of both increasing the efficiency and the speed of detection. To this end, this study integrates the grating diffraction and transport-equation analyses. In the electromagnetic-diffraction part, updated simulation tools developed by the authors for a general illumination and refractive-indexes database are employed. In the carrier-transport part, analytic results for simple geometry are used and simulation using MATLAB® PDE toolbox for 2D field geometry is performed. A part of these results was reported previously by S. Hava and M. Auslender "Design and analysis of low-reflection grating microstructures for a solar energy absorber", Sol. Energy Mat. & Sol. Cells 61, 143 (2000)], where it was shown that the grating approach provides a decent solution for increasing the dc detection efficiency.