For　homo-junction　Si　bipolar　transistor　(Si　BJT)　operation　under　common　emitter,　because　of　self-heating　and　the　positive　feedback　of　thermoelectricity,　thermal　runaway　occurs　easily　at　high　collector-emitter　voltage　and　high　current,　this　decreases　the　safe　operation　area　(SOA)　of　transistors.　In　this　paper,　due　to　negative　feedback　of　thermoelectricity,　the　negative　differential　resistance　(NDR)　characteristics　of　Si/SiGe/Si　double　hetero-junction　bipolar　transistors　(DHBTs)　with　heavily　doped　base　at　high　currents　are　observed.　A　new　interpretation　to　this　phenomenon　is　given.　This　may　be　resulted　from　Auger　recombination　in　the　base　and　decrease　in　current　gain　at　high　current　as　temperature　rises　by　self-heating　effects.　As　a　result,　this　phenomenon　has　benefit　to　improve　anti-burnout　capability　of　bipolar　transistors.　The　results　indicate　power　Si/SiGe/Si　HBTs　have　self-regulating　ability　and　confirm　that　they　are　suitable　for　high　power　applications.　©　2004　IEEE.