Effect of Cycle Annealing Parameters on Dislocation Density Reduction for HgCdTe on Si

Abstract

In our previous study of ex situ thermal cycle annealing (TCA) of molecular beam epitaxy (MBE)-grown mercury cadmium telluride (HgCdTe) on CdTe/ Si(211) composite substrates we showed consistent dislocation density reduction to $1 9 10 6 cm À2 . In this work, we have extended our study to understand the effects of TCA at lower temperatures and fewer cycles than studied previously. By examining TCA performed at the lower end of the temperature spectrum (as low as 385°C), we are able to show an exponential correlation between etch pit density (EPD) and temperature. Varying the number of cycles also shows a similar exponential correlation with EPD. These results suggest that these are the two major factors driving dislocation annihilation and/or coalescence. In this paper, we discuss the theoretical mechanism behind dislocation reduction, both at the surface and throughout the bulk of the HgCdTe layer.

Low threading dislocation density GaAs growth on on-axis GaP/Si (001)

“…4 More specifically, the thermal stress due to the differential thermal expansion coefficients force the TDs to glide during TCA, and two approaching 60 MDs either fuse or annihilate depending on their Burgers vectors. 29,30 Also, note that some of the remaining TDs appear aligned in the [110] direction in Fig. 3(a), indicating a less effective dislocation reduction for b-type dislocations.…”

Infrared Photodiodes on II-VI and III-V Narrow-Gap Semiconductors

“…A strong correlation between minority carrier lifetime and dislocation density was observed. The effect of temperature cycling on the dislocation density was also investigated by Farrell et al (Farrell, 2011). In-situ and ex-situ thermal cycle annealing methods have been used to decrease dislocation density in CdTe and HgCdTe.…”

Dislocation Analysis in (112)B HgCdTe/CdTe/Si

“…From Eqs. (14) and (16), the activation energy for dislocation motion E and the proportionality constant a can be obtained from the slope and intercept of Fig. 1.…”

“…Since all the parameters (E, a, and n) in Eqs. (13) and (14) are known, the TCA theory can now be tested against experimental data. In all the following figures no adjustable parameters are used to fit the theory to the data.…”

“…[12][13][14] The resulting reduction in dislocation density due to TCA may have a significant impact upon FPA performance if the defect density can be reduced below $5 9 10 5 cm À2 . The goal of this effort is to analyze the dislocation reduction of MBE (112)B HgCdTe/CdTe/Si by TCA.…”