N-Polar III–Nitride Green (540 nm) Light Emitting Diode

Abstract

We report the demonstration of a N-polar InGaN based green light emitting diode (LED) grown by N 2 plasma-assisted molecular beam epitaxy (PAMBE). High quality multiple quantum well LEDs with In 0:29 Ga 0:71 N quantum wells were grown at a temperature of 600 C by applying a new growth model. LED structures exhibited green emission, and electroluminescence measurements on the test structure showed peak emission wavelengths varying from 564.5 to 540 nm. The full width at half-maximum reduced from 74 to 63 nm as the drive current was increased to 180 A/cm 2. This work is the first demonstration of an N-polar LED with emission in the green wavelength range.

Investigation on the origin of luminescence quenching in N-polar (In,Ga)N multiple quantum wells

“…However, the N-polar ½000 1 orientation was rather disregarded for device prospects. 3,5 Still, a much poorer photoluminescence (PL) was reported for N-polar multiple quantum wells (MQWs) grown by metal organic chemical vapor deposition (MOCVD) compared to Ga-polar ones. 1 Yet, N-polar nitrides have redrawn an increasing interest thanks to recent breakthroughs in the field of transistors and green emitters.…”

Suppression of electron overflow and efficiency droop in N-polar GaN green light emitting diodes

“…17,18 However, there have been very few experimental reports on InGaN/GaN quantum well emitters with reverse polarization due to the inherent challenges in growth and fabrication. [19][20][21] Ga-polar p-down devices have been investigated but found to be impractical due to the difficulty in obtaining low contact resistance to the etched p-type region and current crowding in resistive p-type epitaxial layers. 20 In this letter, we investigate p-top junctions on a Npolar substrate to investigate the effects of reverse polarization in N-polar LEDs and show (i) that the efficiency droop can be correlated with electron overflow effects and (ii) that the reversal of built-in polarization fields in these N-polar LEDs can be used to mitigate electron overflow and efficiency droop at higher currents.…”

Unipolar vertical transport in GaN/AlGaN/GaN heterostructures

“…As shown in the energy band diagram ( Figure 3(c)), a thin InGaN 20 layer provides a polarization-induced dipole that creates an electrostatic barrier that would not be permeable to percolation effects. The InGaN layer was grown in In-rich conditions using a Ga/N flux ratio of 0.40 at a temperature of 540 C. [20][21][22][23] In the energy band diagram simulation, background density of 10 16 cm À3 n-type dopants for GaN layer was included. The AlGaN layer was used to further provide a dipole at the UID GaN/AlGaN interface, which leads to a flat energy band profile at equilibrium.…”