The simple Single-Electron Memory Cell proposed by Nakamura et al. was fabricated and studied at Notre Dame by Kameshwar Yadavalli. The lateral gap between control and floating gate (FG)  is expected to act as a barrier single-electron tunneling. As we discovered, this happens only for very narrow gaps (below 2 nm), when direct tunneling is responsible for the charging of the FG. Each step corresponds to a transfer of single electron to the FG. The back gate is used to cancel out direct coupling from CG to FG.