Properties of N-polar InGaN/GaN quantum wells grown with triethyl gallium and triethyl indium as precursors

N-polar InGaN/GaN multi quantum wells (MQWs) were grown by metal organic chemical vapor deposition (MOCVD) using a methyl-free process with triethyl gallium (TEGa) and triethyl indium (TEIn) as precursors allowing the demonstration of N-polar (In,Ga)N layers with residual carbon impurity concentrations as low as 2 × 10¹⁶ cm⁻³, which was about one order of magnitude lower compared to samples grown with trimethyl indium (TMIn) as the indium precursor. The residual oxygen concentration in the samples ranged between 3 and 5 × 10¹⁶ cm⁻³. Interestingly the significantly lower carbon content in the samples grown with TEIn resulted only in a slight increase of the quantum well luminescence compared to the samples grown with TMIn. Independent of the indium precursor used, the luminescence of the N-polar MQWs was significantly less intense compared to complimentary Ga-polar samples, which were also grown for comparison. (paper)