Making a chip is like painting in layers through stencils. Diamond has a special trick: if you cover its surface with hydrogen, a thin sheet just under the surface starts to conduct electricity by itself. That sheet is the transistor's channel.

Four to six masks: gold ohmic contacts (which also protect the hydrogen termination), oxygen-plasma isolation outside the device, a wet etch that opens the gate gap, optional NO₂ exposure to raise the hole density, atomic-layer-deposited Al₂O₃, and the gate metal. The two-dimensional hole gas forms by surface transfer doping, with no dopant atoms at all.

Flow after chapter 3 and PDK-0 (chapter E2). Surface transfer doping requires a negative-electron-affinity C–H surface and an acceptor layer; ALD Al₂O₃ stabilizes the hole gas to 400 °C. Oxygen termination isolates devices and keeps NV centers in the negative charge state, which is why qubit windows in PDK-0 are drawn on the ISO layer.