AVS 50th International Symposium
    Electronic Materials and Devices Thursday Sessions
       Session EM-ThM

Paper EM-ThM6
Indium-Based Ohmic Contacts to n-Type Gallium Antimonide

Thursday, November 6, 2003, 10:00 am, Room 321/322

Session: Materials for Interconnects and Contacts to Semiconductors
Presenter: J.A. Robinson, The Pennsylvania State University
Authors: J.A. Robinson, The Pennsylvania State University
S.E. Mohney, The Pennsylvania State University
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Antimonide based compound semiconductors are promising for a variety of optoelectronic and electronic devices. For some of these devices, shallow ohmic contacts to n-type GaSb are required. Among the ohmic contacts that have been developed for this semiconductor, indium-bearing contacts have provided the lowest specific contact resistances. These contacts offer the possibility of lowering the bang gap of the semiconductor and the barrier height at the metal/semiconductor interface through the formation of InGaSb near the metal/semiconductor interface. However, no studies have been reported demonstrating indium-bearing contacts that remain very shallow, penetrating only tens of nanometers into the semiconductor. Furthermore, the surface morphology of these contacts can be poor due to In agglomeration. Using Pd and In, we are engineering shallow In-based contacts with improved surface and interfacial morphology. To achieve this goal, we are combining an investigation of the phase equilibria in the relevant multi-component systems and an understanding of the kinetics of reaction at the Pd/GaSb interface. In this presentation, we describe the formation of newly identified ternary phases in the Pd-Ga-Sb system, the kinetics of reaction at the Pd/GaSb interface, and the formation of ohmic contacts containing Pd and In on n-type GaSb (n = 2.8 x 10@super 18@ cm@super -3@). By choosing the proportions of Pd and In with guidance from multi-component phase diagrams and by minimizing the sheet resistance of the metallization itself, we have achieved to date contact resistances as low as .085 ohm-mm and specific contact resistances as low as 2 x 10@super -6@ ohm-cm@super 2@.