Authors: Y Fourreau K Pantzas G Patriarche V Destefanis
Publish Date: 2016/05/03
Volume: 45, Issue: 9, Pages: 4518-4523
Abstract
The performance of mercury cadmium telluride MCTbased infrared IR focalplane arrays is closely related to the crystalline perfection of the HgCdTe thin film In this work Terich 111Boriented HgCdTe epilayers grown by liquidphase epitaxy on CdZnTe substrates have been studied Surface atomic steps are shown on asgrown MCT materials using atomic force microscopy AFM and whitelight interferometry WLI suggesting stepflow growth Locally quasiperfect surface spirals are also evidenced A demonstration is given that these spirals are related to the emergence of almost pure screw threading dislocations A nondestructive and quantitative technique to measure the threading dislocation density is proposed The technique consists of counting the surface spirals on the asgrown MCT surface from images obtained by either AFM or WLI measurements The benefits and drawbacks of both destructive—chemical etching of HgCdTe dislocations—and nondestructive surface imaging techniques are compared The nature of defects is also discussed Finally stateoftheart threading dislocation densities in the low 104 cm−2 range are evidenced by both etch pit density EPD and surface imaging measurements
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