Heterojunction bipolar transistor and method of manufacturing
Enquist, P. (2000). IPC No. U.S.Heterojunction bipolar transistor and method of manufacturing (Patent No. 6107151.)
A heterojunction bipolar transistor structure grown withorganometallic vapor phase epitaxy (OVMPE) which uses zinc as thebase dopant. The HBT structure has eight layers grown on asubstrate, including n-type doped first, second, third, fifth,sixth, seventh, and eighth layers and a p-type zinc doped fourthlayer. The first layer is a thicker, moderately doped n-type layercompared to the thinner, higher doped n-type second layer. Theseventh layer is a thicker, moderately doped n-type layer comparedto the thinner, higher doped n-type eighth layer. In addition, someor perhaps all of the layers have a high V/III ratio of 10-100 usedto increase the gallium vacancies and reduce the diffusion of zincfrom the base layer. Further, annealing of the structure isperformed during growth to minimize gallium interstitials and toinhibit the diffusion of zinc.