This paper reports a novel zinc diffusion method for forming emitters in GaSb thermophotovoltaic cells. A closed quartz-tube diffusion system using Zn-Ga alloys as the diffusion source was designed to realize p-type doping in N-GaSb wafers. The surface diffusion region showing a high concentration of zinc was suppressed by this diffusion method, and the GaSb cells fabricated using this method showed good quantum efficiency in the near-infrared bands. Compared to that of the conventional pseudo-closed-box diffusion method, the controllability of the etch-back process after front-side metallization is significantly improved, and the cost of the cell fabrication is reduced because no protective gas is required during the diffusion process. (C) 2013 Elsevier B.V. All rights reserved.