Enhancement of optical phonons limited electron mobility in an AlGaN step-shaped quantum well

Achieving high conductivity in n-type AlGaN of deep ultraviolet light-emitting diodes is still a challenge nowadays. In the Lei–Ting equilibrium equation method framework, a four-layer quantum well with n-Al 0.7 Ga 0.3 N barriers and an Al 0.55 Ga 0.45 N/Al x Ga 1− x N bi-component well could obtain a much higher electron mobility μ T than that in a single-component quantum well over a relatively broad Al content range 0.56 < x < 0.68. While the built-in electric field induces strong confinement, pushing the electron to the interface, the optical phonon mode at this interface could be component-modulated to disappear due to the ternary mixed crystal effect. A significant enhancement of electron mobility can be achieved by avoiding the scattering from optical phonons at the interface where the electron gathers. The optical phonon limited μ T could reach 7966 cm 2 /V s at x = 0.58, which is almost five times of 1518 cm 2 /V s in the case of x = 0.55 and ten times of 822 cm 2 /V s for x = 0.70. Such a step-shaped quantum well with high electron mobility could be an alternate or insert layer to the high Al content n-layer to alleviate the current crowding.