Title :
Ohmic contact technology in III-V nitrides using polarization effects in cap layers
Author :
Gessmann, Th. ; Graff, J.W. ; Li, Y.-L. ; Waldron, E.L. ; Schubert, E.F.
Author_Institution :
Dept. of Electr. & Comput. Eng., Boston Univ., MA, USA
Abstract :
A novel technology for low-resistance ohmic contacts to III-V nitrides is presented. The contacts employ polarization-induced electric fields in strained cap layers grown on lattice-mismatched III-V nitride buffer layers. With appropriate choice of the cap layer, the electric field in the cap layer reduces the thickness of the tunnel barrier at the metal contact/semiconductor interface. Design rules for polarization-enhanced contacts are presented giving guidance for composition and thickness of the cap layer for different III-V nitride buffer layers. Experimental results for ohmic contacts with p-type InGaN and GaN cap layers are markedly different from samples without a polarized cap layer thus confirming the effectiveness of polarization-enhanced ohmic contacts.
Keywords :
III-V semiconductors; contact resistance; electric fields; ohmic contacts; polarisation; semiconductor device metallisation; semiconductor-metal boundaries; tunnelling; GaN; III-V nitrides; InGaN; lattice-mismatched nitride buffer layers; low-resistance ohmic contacts; metal contact/semiconductor interface; ohmic contact technology; polarization-enhanced contacts; polarization-induced electric fields; strained cap layers; tunnel barrier; Buffer layers; Capacitive sensors; Gallium nitride; III-V semiconductor materials; Lattices; Ohmic contacts; Optical polarization; Piezoelectric polarization; Systems engineering and theory; Tunneling;
Conference_Titel :
High Performance Devices, 2002. Proceedings. IEEE Lester Eastman Conference on
Print_ISBN :
0-7803-7478-9
DOI :
10.1109/LECHPD.2002.1146792
