The original carbon-boron reduction method involves heating a mixture of metal oxides, boron sources, and carbon at high temperatures to produce boride ceramics ... hafnium oxide (HfO₂), and boron.
On the front side, the devices featured a boron-diffused emitter, passivated by a multilayer stack of aluminum oxide (AlOx), a SiNx layer, and a silicon oxynitride (SiOyNz) layer as an antireflection coating (ARC).