A semiconductor structure comprising: a dielectric layer (162); an emitter region (140) comprising: a first emitter portion (141) extending through the dielectric layer (162); and a second emitter portion (142) on the first emitter portion and further extending laterally onto the dielectric layer (162); and an additional dielectric layer (163) on the second emitter portion, wherein the dielectric layer (162), the second emitter portion (142), and the additional dielectric layer (163) are wider than the first emitter portion (141), and wherein at least a section of the second emitter portion (142) is narrower than the dielectric layer (162) and the additional dielectric layer (163). Preferably, the second emitter portion (142) increases in width between the dielectric layer (162) and the additional dielectric layer (163)