Benefits of negative polarization charge in n ‐InGaN on p ‐GaN single heterostructure light emitting diode with p ‐side down

Abstract

AbstractThe effects of negative polarization charge at the n ‐InGaN/p ‐GaN interface on the performance of hydride vapour phase epitaxy‐deposited single heterostructure n ‐In0.17Ga0.83N/p ‐GaN light emitting diodes with p ‐side down are investigated. The negative polarization charge at the interface leads to the formation of a two‐dimensional hole gas within the InGaN near the n ‐InGaN/p ‐GaN interface, as well as reducing the barrier for hole injection. In addition, electrons encounter experience a significant barrier for injection across the heterointerface. As a result, superlinear increase in light output as injection current increases below 20 A/cm2 and peak emission wavelength shift from 495 nm to 470 nm are observed. We show that the combination of two‐dimensional hole‐gas formation on the n ‐InGaN side of the hetero‐interface and enhancement of the electron barrier to transport across this interface may reduce efficiency droop at high current density without the need for an AlGaN electron blocking layer. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)