n-Type and p-type conductivity control of ZnSe grown by metalorganic molecular beam epitaxy using methyliodide and ammonia

Abstract Electrical properties of ZnSe heavily doped with iodine or nitrogen have been investigated. The film crystals of ZnSe were grown by metalorganic beam epitaxy with methyliodide or ammonia as a dopant source. Iodine doping provides highly conductive n-type ZnSe with resistivity as low as 0.02 Ω cm and a carrier concentration of 2.2×10 18 cm −3 at room temperature. For ZnSe:N, ohmic electrodes have been formed with gold by annealing at 360°C for 5 min in N 2 atmosphere. The activation energy of p-type conductivity, E A , is 90–110 meV when the growth temperature ( T g ) is 350°C, while ( E A is 80–100 meV when T g =400° C . The acceptor concentration N A decreases from 9×10 16 −3×10 17 to 3×10 16 −7X10 16 cm −3 as T g is elevated from 350 to 400°C. However, the difference between the acceptor and residual donor concentration ( N A − N D ) is about 5 times larger for 400°C than for 350°C. N A − N D is 4×10 15 −7×10 15 cm −3 for 350°C and 2×10 16 −4×10 16 cm −3 for 400°C. This result indicates that electrical properties of the p-type ZnSe:N are improved as T g increases. Photoluminescence properties of n-ZnSe:I and p-ZnSe:N are also reported.