TECHNOLOGY FOCUS - ELECTRONICS - Preferred Method: The method further comprises: forming at least one III-nitride device layer above the buffer layers, where the III-nitride device layers are coherently grown on or above the doped buffer layers; and increasing or maximizing a critical thickness of the buffer layers by the doping, where the doping is such that the critical thickness is thicker as compared to without the doping. In the method: the buffer layers are doped with a doping concentration of more than 3 x 1018 cm-3, where the buffer layers are doped with silicon; an indium composition of the III-nitride device layers is at least 30%, or sufficient for the device to emit light having a peak intensity at a wavelength in a green wavelength range or longer; and the doping, a thickness and/or a composition of the doped buffer layers are such that the doped buffer layers have a thickness near or greater than their critical thickness for relaxation. In the method, the doping: reduces or prevents the formation of misfit dislocations with line directions inclined with respect to an in-plane m- or a-direction of the III-nitride device layers formed on or above the doped buffer layers; prevents the formation of additional threading dislocations during growth of the buffer layers and the III-nitride device layers; and reduces or prevents formation of misfit dislocation lines resulting from c-plane slip, where the line direction is parallel to an in-plane m- or a-direction of the III-nitride device layers formed on or above the doped buffer layers. Preferred Components: The III-nitride device layers: include an active region (338), where the III-nitride device layers have a threading dislocation density of less than or equal to 107 cm-2; and comprise at least one waveguiding layer and/or at least one cladding layer (340). The buffer layers comprise indium-gallium-nitride or aluminum-gallium-nitride. In the device structure: the doping concentration is more than 3 x 1018 cm-3; the doping concentration and a thickness or composition of the doped buffer layers is such that the doped buffer layers are near or greater than their critical thickness for relaxation; and the III-nitride device layers are the layers of a laser diode (preferred), LED, solar cell or transistor, where the III-nitride device layers include the cladding layers, the waveguiding layers and the active region. The device structure further comprises the III-nitride device layers formed above the buffer layers. EXAMPLE - No suitable example given.