Surface Passivation of InGaAs/InP p-i-n Photodiodes Using Epitaxial Regrowth of InP
Osvaldo M. Braga, Cristian A. Delfino, Rudy M. S. Kawabata, L. D. Pinto, G. S. Vieira, M. P. Pires, P. L. Souza, E. Marega, John A. Carlin, Sanjay Krishna
Abstract
The use of epitaxial regrowth of InP on lattice-matched In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.53</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.47</sub> As for passivation of photodiodes lateral mesa surfaces is investigated. The effect of the regrown layer was examined by photoluminescence and dark current measurements and compared with results obtained with SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> passivation layers. The integrated intensity of steady-state photoluminescence of InGaAs covered by InP increased by a factor between 15.5 and 58.9, depending on the excitation wavelength, denoting a strong reduction of nonradiative recombination. This reduction is expected to be the result of a strong reduction of intragap surface states. For the same photoluminescence measurements, both SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> oxide passivation instead showed a reduction of the photoluminescence intensity. The dark currents of p-i-n photodiodes showed less striking results, a fact that we claim, probably is related to residual doping of the InP regrown layer.