Growth and photoluminescence studies of Al-rich AlN∕AlxGa1−xN quantum wells

Abstract

A set of AlN∕AlxGa1−xN (x∼0.65) quantum wells (QWs) with well width Lw varying from 1to3nm has been grown by metal organic chemical vapor deposition. Low temperature photoluminescence (PL) spectroscopy has been employed to study the Lw dependence of the PL spectral peak position, emission efficiency, and linewidth. These results have shown that these AlN∕AlGaN QW structures exhibit polarization fields of ∼4MV∕cm. Due to effects of quantum confinement and polarization fields, AlN∕AlGaN QWs with Lw between 2 and 2.5nm exhibit the highest quantum efficiency. The dependence of the emission linewidth on Lw yielded a linear relationship. The implications of our results on deep ultraviolet optoelectronic device applications are also discussed.

Effect of growth temperature of initial AlN buffer on the structural and optical properties of Al-rich AlGaN

“…Furthermore, cracking in AlGaN grown on AlN buffer is suppressed because of in-plane compressive stress. Therefore, AlN buffer layers have been widely used for Al-rich AlGaN epilayers and various device structures, either by low temperature (LT) nucleation [7][8][9][10] or directly high-temperature (HT) growth [11][12][13][14]. However, there have been no detailed reports about the effect of initial AlN buffer, such as its growth temperature, on structural quality and optical property of high Al-content AlGaN epilayers.…”

MOCVD growth of semipolar AlxGa1−xN on m‐plane sapphire for applications in deep‐ultraviolet light emitters

“…Recently, there has been a growing interest in nonpolar and semipolar III‐nitride quantum structures for their potential advantages in reducing the injection current dependence of the emission wavelength in the corresponding optoelectronic devices, and enhancing their external quantum efficiency 1–7. Conventional InGaN and AlGaN multiple quantum wells (MQWs) grown along the polar [0001] c ‐direction are known to exhibit spontaneous and strain‐induced piezoelectric fields 8–10. Such a phenomenon tends to lower the energy of radiative transitions, and decrease the charge carrier recombination probability as well due to the reduced overlap of hole and electron wave functions.…”

Effect of crystal-field split-off hole and heavy-hole bands crossover on gain characteristics of high Al-content AlGaN quantum well lasers

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] In contrast to visible nitride LEDs, 1-13 advances have only been realized for deep UV LEDs recently. Recent works have been reported for low [26][27][28][29] and high 23,30,31 Al-contents AlGaN QWs. The pursuit of AlGaN deep UV lasers is still challenging 23-29 due to ͑1͒ growth challenges of high Al-content AlGaN and ͑2͒ lack of understanding in gain characteristics of the quantum well ͑QW͒ employed for deep UV laser.…”