Native GaN and AlN substrates cut out of single-crystal boules provide threading dislocations in on-grown III-nitride materials with the density much lower than that observed in structures on conventional sapphire or SiC wafers. The native substrates are also expected to enable an easy choice of growth surface orientation that controls the crystal polarity and, hence, the distribution of polarization charges in a nitride heterostructure. The impact of these factors on the bandgap engineering of advanced electronic and optoelectronic devices is discussed in this paper in terms of numerical simulation with the focus on high-electron mobility transistors and light-emitting diodes. (c) 2005 Elsevier B.V. All rights reserved.