Determination of Secondary-Ions Yield in SIMS Depth Profiling of Si, Mg, and C Ions Implanted Gan Epitaxial Layers

We investigated depth profiles of Si, Mg, and C ions implanted into GaN epitaxial layer using secondary-ion mass spectroscopy (SIMS). GaN layers were grown by metal-organic chemical vapor deposition (MOCVD) on sapphire substrates. Si, Mg, and C ions were implanted at energies of 65, 52, and 30 kV using fluencies of 10
¹⁵
, 1.1×10
¹⁶
I and 5.6×10
¹⁶
cm
^-2
, respectively, so that maximum distribution was located ~50 nm below the GaN layer surface with maximum impurity concentration reaching 10
¹⁹
, 10
²⁰
, and 5×10
¹⁹
cm
^-3
. We observed a good agreement between measured ion profiles and theoretical ion distributions calculated using SRIM This allowed us to determine the yield of several secondary-ions measured by SIMS. It was found that SiN, GaNMg-, and C secondary-ions are most sensitive for determination of Si, Mg, and C impurity concentration in MOCVD grown GaN films, respectively.