A monolithic cell structure can be formed into thin crystalline silicon wafers by forming heavily doped juxtaposed regions of opposite polarity that electrically isolate adjacent devices while simultaneously facilitating their series interconnection through the formation of a low impedance junction. These opposite polarity regions can each be formed by a laser to melt and dope right through the thickness of a thin wafer, or instead since emitters are normally quite shallow, one isolation region may be formed by a heavy diffusion of dopants of opposite polarity to the emitter, as long as it is deep enough to isolate the emitters of the adjacent cells. By this means, a wafer can be divided up into many smaller series connected cells creating a high voltage, low current structure. Such a structure enables the active devices to be made without any metal contacts, which are usually required to carry larger electrical currents relatively long distances, but in doing so, compromise the cell’s simplicity, durability, cost and performance. The methods of isolation and interconnection via both laser and diffusion to create structures are investigated with supportive modelling.
Conference Programme