A STUDY ON STRONG MEMORY EFFECTS FOR MG DOPING IN GAN METALORGANIC CHEMICAL-VAPOR-DEPOSITION

Mg doping response was studied for GaN metalorganic chemical vapor dep osition (MOCVD) for the first time. The delay time was observed betwee n Mg atom incorporation into the growing layer and supplying Mg source to the reactor, in spite of the quick response for doping turn off. T he delay time increased steeply with decreasing Mg source flow rate. T he delay was considered to originate from adsorption of Mg source mole cules to the reactor wall (memory effect). A large Mg sticking coeffic ient and the existence of a saturated amount of Mg source molecules ad sorbed to the reactor wall were suggested. Reducing the memory effect by purging the inlet nozzle of the reactor with the mixed source gas t o be used to grow next layer during growth interruption, the doping re sponce was improved significantly and Mg concentration was controlled down to 5 X 10(16) cum(-3).