 In particular the HEBT does not require as tight parametric control during epitaxial growth, that equivalent abrupt or graded emitter structures might.This is very important as it is evident from scanning ion mass spectrometry data that out-diffusion base dopant into the emitter junction is difficult to control, as the base is, in general, very highly doped in order to enhance performance.The HEBT is well positioned as a potential candidate for key roles in high-frequency optoelectronic markets, similar to the Heterojunction bipolar transistor.