We investigate the mechanism for the improvement of p-type doping efficiency in Mg-Al0.14Ga0.86N/GaN superlattices(SLs).It is shown that the hole concentration of SLs increases by nearly an order of magnitude,from 1.1×1017 to 9.3×1017cm-3,when an AlN interlayer is inserted to modulate the strains.Schro¨dinger-Poisson self-consistent calculations suggest that such an increase could be attributed to the reduction of donor-like defects caused by the strain modulation induced by the AlN interlayer.Additionally,the donor-acceptor pair emission exhibits a remarkable decrease in intensity of the cathodoluminescence spectrum for SLs with an AlN interlayer.This supports the theoretical calculations and indicates that the strain modulation of SLs could be beneficial to the donor-like defect suppression as well as the p-type doping efficiency improvement.
The influence of the width of a lattice-matched Al 0.82 In 0.18 N/GaN single quantum well (SQW) on the absorption coefficients and wavelength of the intersubband transition (ISBT) has been investigated by solving the Schrdinger and Poisson equations self-consistently.The wavelength of 1-2 ISBT increases with L,the thickness of the single quantum well,ranging from 2.88 μm to 3.59 μm.The absorption coefficients of 1-2 ISBT increase with L at first and then decrease with L,with a maximum when L is equal to 2.6 nm.The wavelength of 1-3 ISBT decreases with L at first and then increases with L,with a minimum when L is equal to 4 nm,ranging from approximately 2.03 μm to near 2.11 μm.The absorption coefficients of 1-3 ISBT decrease with L.The results indicate that mid-infrared can be realized by the Al 0.82 In 0.18 N/GaN SQW.In addition,the wavelength and absorption coefficients of ISBT can be adjusted by changing the width of the SQW.
