화학공학소재연구정보센터
Journal of Materials Science, Vol.52, No.18, 10879-10885, 2017
Deactivation of electrically supersaturated Te-doped InGaAs grown by MOCVD
Achieving and sustaining the highest doping level possible in InGaAs is critical for the reduction of contact resistance in future microelectronic applications. Tellurium (Te) is a very promising n-type dopant with high reported n-type doping densities. However, the stability of this dopant during post-growth thermal processing is unknown. Supersaturated Te-doped InGaAs layers were grown by MOCVD at 500 degrees C. The electrically active concentration of Te doping was 4.4 x 10(19) cm(-3) as grown. The thermal stability of the Te was investigated by studying the effect of post-growth annealing between 550 and 700 degrees C on the electrical activation. At all temperatures, the electrical activation decreased from its starting electron concentration of 4.4 x 10(19) cm(-3) down to 6-7 x 10(18) cm(-3). The rate of deactivation was measured at each temperature, and the activation energy for the deactivation process was determined to be 2.6 eV. The deactivation could be caused by either Te-Te clustering or a Te-point defect reaction. HAADF-STEM images showed no visible clustering or precipitation after deactivation. Based on previous ab initio calculations that suggest the VIII population increases as the Fermi level moves toward the conduction band, it is proposed that formation of isolated point defect complexes, possibly a Te-VIII complex, is associated with the deactivation process.