Improved Vertical Carrier Transport for Green III-Nitride LEDs Using <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mo stretchy="false">(</mml:mo><mml:mi>In</mml:mi><mml:mo>,</mml:mo><mml:mi>Ga</mml:mi><mml:mo stretchy="false">)</mml:mo><mml:mrow><mml:mrow><mml:mi mathvariant="normal">N</mml:mi></mml:mrow></mml:mrow></mml:math> Alloy Quantum Barriers

We report on experimental and simulation-based results using (In, Ga)N alloy quantum barriers in c-plane green light-emitting diode (LED) structures as a means to improve vertical carrier transport and reduce forward voltage (V F). Three-dimensional device simulations that include random alloy fluctuations are used to understand carrier behavior in a disordered potential. The simulated current density-voltage (J-V) characteristics and modified electron-hole overlap |F mod | 2 indicate that increasing the indium fraction in the (In, Ga)N quantum barriers leads to a reduced polarization discontinuity at the interface between the quantum barrier and quantum well, thereby reducing V F and improving |F mod | 2. Maps of electron and hole current through the device show a relatively homogenous distribution in the XY plane for structures using GaN quantum barriers; in contrast, preferential pathways for vertical transport are identified in structures with (In, Ga)N barriers as regions of high and low current. A positive correlation between hole (electron) current in the p-side (n-side) barrier and indium fraction reveals that preferential pathways exist in regions of high indium content. Furthermore, a negative correlation between the strain ε zz and indium fraction shows that high indium content regions have reduced strain-induced piezoelectric polarization in the Z direction due to the mechanical constraint of the surrounding lower indium content regions. Experimentally, multiple quantum well green LEDs with (In, Ga)N quantum barriers exhibit lower V F and blue-shifted wavelengths relative to LEDs with GaN quantum barriers, consistent with simulation data. These results can be used to inform heterostructure design of low V F , long-wavelength LEDs and provide important insight into the nature of carrier transport in III-nitride alloy materials