Determination of hydrogen in GaMnN and GaMnMgN by nuclear reaction analysis

Gallium nitride is a novel material for short wavelength (blue) optoelectronics. Our previous investigation showed that Mn doped GaN has paramagnetic or antiferromagnetic properties opening new possible applications. The high concentration of magnetic ions possibly allows for the use of such a material in magnetooptic and spintronic devices. GaMnN and GaMnMgN powders were prepared by heating mixtures of gallium and manganese powder or powders of gallium nitride and manganese in a stream of ammonia at the temperature up to 1250°C. The powders have a grain size about 1-10 µm and they contain more than 2% of manganese by weight. Powders of doped GaN were prepared in a series of technological processes at various temperatures, ammonia flow rates and concentration of dopants in initial mixtures. Since hydrogen largely attributes to the passivation of p-dopants it plays an essential role in determination of electrical properties of these materials. Hydrogen content analysis was performed by the NRA method using the 1H(15Na,alpha gamma)12C reaction. This reaction has a sharp resonance of the cross-section at 6.385 MeV. Therefore it is possible by changing the incident 15N beam energy to measure depth distribution of hydrogen. It was found out that hydrogen concentration in our materials was below 1.5at%.