Study Of GaSb Thermophotovoltaic Cells And Its Antireflection

GaSb has long been considered as a potential candidateâ…¢-â…¤semiconductor material for near-infrared and infrared devices and in the past four decades,it has been intensively studied and wildly used to fabricate thermophotovoltaic system as the energy conversion units due to its ideal match between the spectral response of the thermophotovoltaic cells and the infrared radiation spectra.In this paper,first,some physics characteristics of GaSb and basic principle of solar cells are reviewed and then several alternative strategies are investigated that allow to build shallow PN junction with heavily doped on n type GaSb substrates.Compare with the results,we finally utilize the twice diffusion,associating with anodic oxidation and building drift electric field under the anode methods to fabricate GaSb cells.The highest photoelectric conversion efficiency is beyond 6%(AM1.0,25℃).Another focus of this paper lies in the quality of antireflection layer and surface texture. Two traditional low cost and easy operated ways,anodic oxidation and chemical etching,are chosen.Through increasing the amount of ions of the anodic oxide solution,bias voltage is reduced effectively and suitable oxidation rate is obtained by modifying the pH value and the composition of solutions.Atom Force Microscopy(AFM) was investigated for analyzing the roughness of thin film and found that the final current density and applied voltage determine the quality and homogeneity of thin film that the reason why we decreased the bias voltage.The surface texture is considered as one of the most effective methods to optimize the reflection in all range of spectra based on the multiple reflection of incident light.However, chemical etching technique used to passivate the GaSb cells' surface is the first time reported. We attempted to use different oxide agencies to form stable texture structure which could be implemented as the antireflection coating on GaSb cells and Scanning Electronic Microscopy (SEM) was utilized to observe the surface structure.Several kinds of evenly distributed texture were achieved in n-type and p-type GaSb substrates,respectively.Especially on p-type GaSb substrate,etched for 5 minutes in the solution of HCI:HNO₃:H₂O(2:1:6),regular triangle structure,whose top angle was 63.1 and defined by two equivalent { 111 } facets,was obtained.