GaMnN growth on GaAs (100) using a GaN single precursor via molecular beam epitaxy was undertaken. The grown layers revealed p-type conduction. It is confirmed that p-GaMnN reveals room temperature ferromagnetism with hysteresis loop having a coercivity of ∼100 Oe. The segregated phase showing a transition temperature of ∼200 K is assigned to Mn3GaN, and which enhances the conductivity of the surrounding GaMnN region. As a consequence, the GaMnN layer with segregation revealed an anomalous Hall effect at room temperature proving magnetotransport in GaMnN phase. The enhanced conductivity of GaMnN by the highly conductive second phase also revealed the importance of the role of the free carriers in the carrier-mediated ferromagnetism.

A series of GaN:Mg structures were grown in molecular beam epitaxy, using either one or two rf nitrogen sources, and in metalorganic chemical vapor deposition systems with varying Mg flux. Acceptor energies were measured using the Hall effect and admittance spectroscopy techniques. The acceptor energies were found to be different for the two methods, i.e., 135–155 meV for the Hall effect measurement and 80–115 meV for the admittance spectroscopy measurement. The apparently small acceptor energies from the admittance spectroscopy measurement were explained, through a simulation process, by the combined effects of (1) high Mg acceptor concentration with no other free carrier sources, and (2) the Mg emission kinetics assisted by the Frenkel–Poole field effect in the GaN:Mg structures.

Two layer feeding trials were conducted to demonstrate the nutritive and economic values of recently developed high oil corn (HOC) in Korea. A corn-soybean meal-based commercial layer diet was chosen as the control diet. The yellow dent corn in the control diet was replaced with HOC to give an isocaloric diet, or replaced with HOC on a 1:1 basis to give a high energy diet. In Trial 1, 510 23-wk-old ISA Brown layers were allotted to three dietary treatments with five replicates per treatment. In Trial 2, 600 38-wk-old Hy-Line Brown layers were allotted to three dietary treatments, again with five replicates per treatment. Both trials were conducted for 15 wk. To measure the ME values of typical corn and HOC, two metabolism trials were performed with layers and adult roosters. The HOC used in this trial contained approximately 94% higher crude fat (6.60% as-fed basis) compared with typical corns. The gross energy, AMEn, and TME values of HOC, are 5.7 to 7.7% higher than those of typical corns, indicating that the energy use of each corn were similar. Oil from the HOC contains 6.5 to 8.3% more oleic acid and 6 to 7% less linoleic acid than oil from typical corns. HOC feeding, on an isocaloric basis or on 1:1 replacement with typical corn, did not exert any effect on various laying performances, including the physical quality of egg. This result reflects the quality of the commercial diet chosen as the control diet, which was already fairly good, such that the performance was already maximal. The polyunsaturated fatty acid content in yolk from hens fed HOC was higher than that from hens fed typical corns, reflecting higher linoleic acid content in the HOC. HOC feeding decreased the saturated fatty acid content in the yolk, due primarily to decreased palmitic acid. If used alone replacing typical corn completely in a layer diet, the acceptance price of HOC was estimated to be 154 won/kg when the price of typical corn was 131 won/kg (118:100). When both corns were allowed to be used, the acceptance price of HOC increased to 184 won/kg (140:100), indicating that a lot cheaper layer diet can be formulated when both HOC and typical corn are used in laying hen diet formulation.

The effects of Mg codoping on the structural, electronic transport, and magnetic properties of GaMnN films are investigated. Mg was shown to compete with Mn for incorporation into the growing films at impingement, and to replace Mn. The partial replacement of Mn by Mg in GaMnN has resulted in an increase of conductivity of the region. The enhanced transport property due to the highly efficient dopant Mg resulted in a remarkable increase of the saturation magnetization, indicating an interaction between Mn and Mg for the carrier-mediated ferromagnetism. The increased carrier population by Mg codoping enabled a full mediation among the Mn atoms, and consequently, suppressed the paramagnetic rise in the temperature-dependent magnetization measurement.

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