From the simulation results for the lateral and vertical devices obtained in the previous sections it is obvious that vertical devices have a relatively flat response over the visual spectrum, while the lateral devices have a better blue response. By combining the lateral and vertical devices new structures can be designed. In fact very minor changes are needed to be done for each device. For the photodiode structures all is needed is to make the exposure window opening large enough so that the edges of the diode are also exposed. Figure 7.11 illustrates the mixed devices.
Figure 7.11: a) A mixed lateral and vertical photodiode. b) A mixed
lateral and vertical bipolar transistor.