| Self-Heating and the Temperature Distribution in Multi-emitter SiGe HBTs |
Sean McAlister High power bipolar transistors often have multiple emitters, to achieve high currents, and efficient use of the whole emitter area. The emitters experience high current densities and are self-heated above the ambient temperature, leading to concerns about thermal run-away and damage to the device. Are the emitters all at the same temperature during operation? To study this we have designed and used multi-emitter SiGe HBTs, with multiple emitter contacts, to examine the temperature distribution in the emitters in such devices. By biasing one emitter at a time and using the other base-emitter junctions as thermometers we have measured the temperature increase in different emitters and effectively the thermal coupling between the emitters.? We will compare the data with simulations for a simple thermal model. Sean McAlister was born in Durban, South Africa and has an M.Sc. degree in Physics from the University of Natal, South Africa. He was then awarded an international scholarship to study Physics at Cambridge University, England where he obtained a Ph.D. in 1971. After 4 years at Simon Fraser University, Vancouver, as a post-doctoral fellow and visiting professor, he moved to the National Research Council of Canada in Ottawa where he is now a Principal Research Officer.He has worked and published in many fields involving solid state physics, including NMR, low temperature transport in metals, alloys, oxides and thin films, magnetism and semiconductor materials.? For the last 15 years he has concentrated on semiconductors and become a device physicist, doing design, simulation and characterization of heterostructure materials and devices, in particular high speed bipolar transistors.He setup and led the device physics efforts at the NRC for over 10 years, leading projects within NRC and collaborating with companies, universities and laboratories in Canada, Singapore, Taiwan and England. He has been an Adjunct Professor at the University of British Columbia, McMaster and Carleton Universities. Other activities have included running the Canadian Semiconductor Technology Conference and serving as Chairman of a Grant Selection committee for a grant awarding agency of the Canadian Government. In 2003 he was selected by the National Research Council and National Science Council of Taiwan, as an Eminent Researcher.For relaxation he spends most non-winter weekends improving and enjoying a lakeside cottage near Ottawa. He is an active member of choir which sings classical music, and has toured parts of Canada, France and Germany. |