We examine the bound charge present when the III-nitride alloys, AlGaN, InGaN, and AlInN, are pseudomorphically grown on templates of relaxed GaN, InN, and AIN epitaxial layers. The advantages of yet unrealized heterojunctions, such as AIInN/InN, are compared with the more common AlGaN/GaN heterojunction. Special attention is paid to AlInN/GaN where a lattice matched and a zero total bound charge heterojunction are possible.