Improvement of crystalline quality of CdZnTe epilayers on GaAs(001) substrates with a two-step growth by Close Spaced Sublimation

Abstract

Abstract A two-step growth process of CdZnTe(001) epilayers on GaAs(001) substrates by Close Spaced Sublimation (CSS) is proposed. The first step, or a so-called pre-growth at low temperature of 350\u202f°C generates more compact nucleation layer than the second step growth at 430\u202f°C, which is more efficient for accelerating grain coalescence and annihilation of defect. Both the double crystal X-ray rocking curve (DCXRC) and the photoluminescence (PL) results prove that CdZnTe film with the best crystalline quality is obtained with the combination of the first step growth at 350\u202f°C and the second growth at 430\u202f°C. Increasing the second step growth temperature from 430\u202f°C to 530\u202f°C and 600\u202f°C deteriorate films crystalline quality due to the increase in thermal stress and Zn content. Current-voltage (I V) measurement and alpha-particle response test indicate that better crystalline quality in CZT film leads to both higher resistivity and better carrier transport property.