Dislocation Reduction of HgCdTe/Si Through Ex Situ Annealing
- First Online:
- 126 Downloads
Current growth methods of HgCdTe/Cd(Se)Te/Si by molecular-beam epitaxy (MBE) result in a dislocation density of mid 106 cm−2 to low 107 cm−2. Although the exact mechanism is unknown, it is well accepted that this high level of dislocation density leads to poorer long-wavelength infrared (LWIR) focal-plane array (FPA) performance, especially in terms of operability. We have conducted a detailed study of ex situ cycle annealing of HgCdTe/Cd(Se)Te/Si material in order to reduce the total number of dislocations present in as-grown material. We have successfully and consistently shown a reduction of one half to one full order of magnitude in the number of dislocations as counted by etch pit density (EPD) methods. Additionally, we have observed a corresponding decrease in x-ray full-width at half-maximum (FWHM) of ex situ annealed HgCdTe/Si layers. Among all parameters studied, the total number of annealing cycles seems to have the greatest impact on dislocation reduction. Currently, we have obtained numerous HgCdTe/Si layers which have EPD values measuring ~1 × 106 cm−2 after completion of thermal cycle annealing. Preliminary Hall measurements indicate that electrical characteristics of the material can be maintained.
KeywordsMercury cadmium telluride HgCdTe thermal cycle annealing (112) etch pit density (EPD) dislocations MBE silicon Si composite substrates
Unable to display preview. Download preview PDF.
- 14.P.S. Wijewarnasuriya, Y. Chen, G. Brill, M. Carmody, R. Bailey, J. Arias, and N.K. Dhar, Proc. SPIE, 6206, 620611 (2006).Google Scholar
- 21.S. Farrell, G. Brill, Y. Chen, P. Wijewarnasuriya, M.V. Rao, N. Dhar, and K. Harris, J. Electron. Mater. 39(1), 43 (2010)Google Scholar