Analysis Of Ingan Surfaces After Chemical Treatments And Atomic Layer Deposition Of Al2o3 For Mu Led Applications

A deep understanding of semiconductors-dielectrics interface properties will provide guidelines to optimize efficient passivation solutions for InGaN/GaN based mu LED. To this end, the quantum wells (QW) semiconductor is of tremendous interest since a lot of surface recombinations are likely to occur at LED active regions edges and are probably responsible for the low mu LED efficiencies. Thus we discuss in this paper about X-ray photoemission (XPS) and wavelength dispersive X-ray fluorescence (WDXRF) characterizations of In0.1Ga0.9N surfaces after acid, basic or sulfur based chemical treatments followed or not by atomic layer deposition (ALD) of Al2O3 thin films with TMA/H2O or TMA/O-2 plasma (plasma enhanced ALD) at 250 degrees C.Depending on chemical treatments, variations of indium related XPS peaks were observed, which did not seem to be significantly affected by deposition of Al2O3 whatever the oxidizing precursor. The extreme surface concentration of indium was probably reduced, suggesting that some chemical pre-treatments for cleaning or passivation steps would have a direct impact on InGaN QW properties at LED edges.After sulfur based chemical treatments, even if sulfur was hardly detected by XPS, complementary measurements by WDXRF and subsequent calibration of the sulfur signal supported evaluation of a low surface concentration of sulfur. Changes of Al2O3 related XPS peaks suggested that the various studied pre-treatments induced different nucleations of first ALD cycles. Then, a clear variation of InGaN surfaces hydrolysis depending on surface treatments was finally highlighted by WDXRF based counting measurements, opening the way to a better understanding of first Al2O3 layers nucleation on InGaN.