Schottky contacts on wide bandgap InGaP grown with phosphorous cracker cells and their thermal reliability

Schottky contacts of various metals to the wide bandgap InGaP grown by molecular beam epitaxy using phosphorous cracker cell, and their thermal reliability were investigated using I-V technique. The as-deposited Au–InGaP diode had a barrier height of 0.91 eV, an ideality factor of 1.12 and a Richardson constant of 14.1 A K−2 cm−2. The contacts of Cu and Ti showed a barrier height of 0.81and 0.80 V, an ideality factor of 1.10 and 1.07, and an effective Richardson constant of 6.4 and 148 A K−2 cm−2, respectively. The Au–InGaP sample was annealed in a nitrogen environment over temperatures ranging from 473 to 623 K with a step of 50 K for ten min at each temperature. The barrier height was found to increase slowly with the annealing temperature upto 523 K and thereafter dropped drastically with a further increase in the annealing temperature. The ideality factor, however, reacted in the opposite direction. The rectifying behaviour of Cu–InGaP structure degraded significantly after an annealing at as low as 473 K. These results can be explained by a model that includes quality of the contact and defects formation due to interdiffusion and penetration of metal into the semiconductor at temperatures over a critic value which is related to the nature of metals and annealing period.