Wide bandgap HBT on crystalline silicon using electron-blocking PEDOT:PSS emitter

Heterojunction bipolar transistors in silicon using a narrow band gap base (e.g. Si/SiGe/Si) are well known and have been in production for many years. However a wide bandgap emitter on silicon has proved elusive (Fig 1(a)). Recently it has been shown that heterojunctions between crystalline silicon and organic semiconductors such as PEDOT or P3HT can block electrons from entering the organic [1, 2]. In this work we used the Si/PEDOT heterojunction to demonstrate a HBT with an organic semiconductor wide bandgap emitter, and a crystalline silicon base.