Patent ID: 6903388
Filing Date: 2005-06-07
Classification: H01L

Abstract:
1. A hetero-junction bipolar transistor comprising: an n-type sub-collector layer that is made of GaAs; an n-type first collector layer that is made of a semiconductor material with a smaller avalanche coefficient than an avalanche coefficient of the sub-collector layer and that is formed on the sub-collector layer; a second collector layer that is made of one of n-type and i-type GaAs with lower dopant concentration than dopant concentration of the sub-collector layer and that is formed on the first collector layer; a p-type base layer that is made of GaAs and that is formed on the second collector layer; and an n-type emitter layer that is made of a semiconductor material with a larger band gap than a band gap of the base layer and that is formed on the base layer.