Exploiting the Benefits of Negative Polarization in n-InGaN/p-GaN Single Heterostructure Light Emitting Diode with p-side Down

In this paper we demonstrate the electrical and optical effects of negative polarization charge at the n-InGaN/p-GaN interface on the performance of single heterostructure n-InGaN/p-GaN LEDs with p-side down. This negative polarization charge at the interface leads to a reduced barrier for hole injection from p-GaN to n-InGaN, with a hole accumulation layer forming within the InGaN near the n-InGaN/p-GaN interface. Electrons encounter a significant barrier for injection from the n-InGaN into p-GaN, compounded by the heterobarrier, making p-GaN behave like an effective electron blocking layer. We show that the combination of 2D 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