We have investigated the influence of carbon on Ge dot growth on Si͑100͒ substrates. To modify the Ge dot structure, submonolayers of carbon were deposited on Ge wetting layers. The Ge deposited on the carbon-covered wetting layer tends to form dome structures instead of hut structures even at a substrate temperature of 500°C. The main effect of C is to enhance a structural transition from huts to domes by influencing the configurational energy of the Ge dots. The dominant factor to determine

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... e dot size is the substrate temperature. Accordingly, small domes with 10-20 nm in diameter were formed by combining techniques of the submonolayer C on the Ge wetting layer and low-temperature deposition.