Multi‐color light emitting diode using polarization‐induced tunnel junctions

Abstract

A multi-color light emitting diode (LED) using two distinct active regions connected via a tunnel junction was grown by rf-plasma-assisted molecular beam epitaxy. The LED is contacted through n-type layers, one of which provides efficient contact to a p-type layer via a second tunnel junction. The tunnel junctions used in the structure use the high polarization fields found in the III-nitrides material system to narrow the depletion width of the junction. Two peaks at 405 nm and 490 nm are observed in the electroluminescence spectrum of the LED, and current-voltage characteristics indicate a turn-on voltage of roughly 7.5 V and dynamic series resistance of 19 ª at 80 mA for a ¿¼¼ µm square device.

Design and demonstration of ultra-wide bandgap AlGaN tunnel junctions

“…2(a)). [16][17][18][19][20][21][22] Due to the polarization discontinuity, sheet charges with density over 10 13 cm -2 are induced at the AlGaN/InGaN heterointerfaces and this reduces the tunneling barrier to less than 3 nm ( Fig. 2(b)), leading to much higher tunneling probability compared to the homojunction tunnel junction.…”

InGaN/GaN tunnel junctions for hole injection in GaN light emitting diodes

“…Recently, tunnel junction device designs exploiting polarization in nitrides and embedded rare earth nitride nanoislands resulted in low resistance GaN tunnel junctions with resistivity as low as 10 -4 Ωcm 2 . 1,[4][5][6][7] In case of the polarization 1,[4][5][6][8][9][10][11] -1 x 10 -3 Ωcm 2 was reported. Realization of such low resistance GaN-based tunnel junctions has generated interest in tunnel junction enabled devices such as tunnel junction LEDs [12][13][14][15] , tunnel junction laser diodes 16 , and multi-junction solar cells 17,18 .…”

Demonstration of forward inter-band tunneling in GaN by polarization engineering

“…In the III-nitride system, efficient inter-band tunneling is inhibited by wider depletion regions due to the larger band gap and dopant solubility limitations in degenerately doped GaN p-n junctions. A solution to this problem is to use the high spontaneous and piezoelectric polarization charge 4,5 along the c-axis of III-nitrides for the design of tunnel junctions with greatly reduced tunneling barrier width 6,7,8,9 . The high polarization charge density at a polar hetero-interface creates a large band bending over a very small distance.…”