Dependence of dielectric-cap quantum-well disordering of GaAs-AlGaAs quantum-well structure on the hydrogen content in SiNx capping layer

Dielectric-cap quantum-well disordering of GaAs-AlGaAs multiple-quantum-well (MQW) structure was carried out using SiN_x capping layer grown by plasma enhanced chemical vapor deposition. There was a dependence of quantum-well disordering (QWD) on the hydrogen content in the SiN_x capping layer, which was varied by changing the NH₃ flow rate during the film growth. The degree of QWD increased with increasing of hydrogen content in the Si_x capping layer. The degree of QWD with SIN, capping layer grown at higher NH₃ flow rate was comparable to that with a 300-nm-thick SiO₂ capping layer at the same rapid thermal annealing condition. This result implies the possibility of obtaining spatially selective disordered MQW structure using SiN_x capping layers grown at different NH₃ flow rates. The effect of different SiN_x capping layers on QWD was characterized semiquantitatively by introducing relative vacancy density