Title :
Low emitter resistance GaAs based HBT´s without InGaAs caps
Author :
Slater, D.B., Jr. ; Enquist, P.M. ; Hutchby, J.A. ; Morris, A.S. ; Trew, R.J.
Author_Institution :
Res. Triangle Inst., Research Triangle Park, NC, USA
fDate :
5/1/1994 12:00:00 AM
Abstract :
Low emitter resistance is demonstrated for AlGaAs/GaAs heterojunction bipolar transistors using Pd/Ge contacts on a GaAs contact layer. The contact resistivity to 2-10×10/sup 18/ cm/sup -3/ n-type GaAs is 4-1×10/sup -7/ /spl Omega/-cm2. These are comparable to contact resistivities obtained with non-alloyed contacts on InGaAs layers. The non-spiking Pd/Ge contact demonstrates thermal stability and area independent resistivity suitable for scaled devices. The substitution of Pd/Ge for AuGe/Ni GaAs emitter and collector contacts reduced by an order of magnitude the emitter-base offset voltage at high current densities and increased fT by more than 15% with significantly improved uniformity for devices with 2 and 2.6 μm wide emitters having lengths two, four and six times the width.
Keywords :
III-V semiconductors; aluminium compounds; contact resistance; gallium arsenide; germanium; heterojunction bipolar transistors; ohmic contacts; palladium; semiconductor-metal boundaries; GaAs contact layer; HBT; Pd-Ge-GaAs-AlGaAs; area independent resistivity; collector contact; contact resistivity; emitter contact; heterojunction bipolar transistors; low emitter resistance; n-type GaAs; nonspiking Pd/Ge contact; scaled devices; thermal stability; Conductivity; Contact resistance; Costs; Current density; Doping; Gallium arsenide; Heterojunction bipolar transistors; Indium gallium arsenide; Thermal resistance; Voltage;
Journal_Title :
Electron Device Letters, IEEE
