Preparation, electrical, thermal and mechanical properties of black lithium tantalate crystal wafers

Abstract

In this work, the effect of surface reduction treatment on the electrical, thermal and mechanical properties of Lithium tantalate (LiTaO3, LT) crystal wafers was investigated by comparing congruent Lithium tantalate (CLT) crystal wafers with deep-reduction black Lithium tantalate (BLT) crystal wafers using a mixture of high-purity aluminium powder and silicon powder as reducing agents. The structural changes of reduced wafers are discussed by XRD. The electrical conductivity of BLT wafers is 6.27 × 10–12 (Ω cm)−1, which is four orders of magnitude higher than the CLT crystal wafers. The Curie temperature and the thermal stability are basically the same with CLT crystal wafers, and the specific heat and hardness are reduced. The data show that high temperature annealing before reduction is conducive to the stress release of CLT crystal wafers, the blackening effect is more easily achieved, and the treated BLT wafer is more anti-static. The results show that the reduction treatment can obviously improve the conductivity of the wafer, so it is easier to improve and eliminate the discharge phenomenon caused by pyroelectric effects in the process of device preparation.