Fabrication of InP DHBTs with 0.1 /spl mu/m wide emitter

InP based double heterojunction bipolar transistors (DHBTs) with emitter width of 0.1 /spl mu/m are reported. Emitter mesa with vertical facet was formed by combination of CH/sub 4//H/sub 2/ reactive ion etching (RIE) and wet etching using two different HCl based solutions. Self-aligned base electrode was formed with 0.1 /spl mu/m thick InP emitter layer, by control of the lateral extent of undercut etching of less than 0.1 /spl mu/m.