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

The 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)