分子束外延生长的GaSb热光伏电池器件特性研究

Research on character of molecular beam epitaxial GaSb thermophotovoltaic(TPV)cells

利用分子束外延的方法在GaSb衬底上生长GaSb热光伏电池单元,制作了两种不同的1 cm×1 cm面积尺寸的热光伏电池单元,它们有着不同的电极形状。通过不断优化分子束外延的生长条件,以期得到高质量的GaSb外延层。AFM图中显示的表面形貌表明器件有着高质量的外延层,其表面形貌的RMS只有1.5?(1?=0.1 nm)。测量和比较了两种热光伏电池的器件特性,包括开路电压、短路电流密度、光电转换效率、填充因子以及暗电流密度。在一个模拟太阳光照射下,热光伏电池单元有着0.303 V的开路电压和27.1 mA/cm2的短路电流密度。和只有简单电极形状的热光伏电池单元进行对比,有栅形电极形状的热光伏电池单元在短路电流密度和填充因子上具有更优异的表现。在红外光的照射下,有栅形电极形状的热光伏电池达到了一个最优的填充因子56.8%。

GaSb thermophotovoltaic cells were epitaxially grown on GaSb substrates by the Molecular Beam Epitaxy(MBE)method.And two kinds of GaSb TPV cells with 1 cm×1 cm dimensions that had different electrode shape were fabricated.In order to obtain high quality GaSb epitaxial layer,the growth conditions of MBE were optimized continuously.The quality of epilayers was good which was shown in the surface morphology characterized by AFM.The root mean square(RMS)of surface morphology was only 1.5 A(1 A=0.1 nm).Device characteristics including open-circuit voltage,short-circuit current density,external quantum efficiencies,fill factor and dark current density of the TPV cells were measured and compared.Under solar simulation,the TPV cells exhibited an open-circuit voltage of 0.303 V and a short-circuit current density of 27.1 mA/cm2.Compared with the TPV cell that had a simple electrode,the TPV cell having the grating electrode showed better performance in short circuit current density and fill factor.Under infrared light illumination,the TPV cell with a grating electrode exhibited an optimal fill factor of 56.8%.