The disclosure provides a lateral bipolar transistor structure with a base layer over a semiconductor buffer, and related methods. A lateral bipolar transistor structure may include an emitter/collector (E/C) layer over an insulator. The E/C layer has a first doping type. A semiconductor buffer is adjacent the insulator. A base layer is on the semiconductor buffer and adjacent the E/C layer, the base layer including a lower surface below the E/C layer and an upper surface above the E/C layer. The base layer has a second doping type opposite the first doping type.