Peculiarities of electron field emission from SiGe nanoislands

The electron field emission and photoassisted field emission from SiGe nanoisland formed by MBE growth are investigated. There are two types of nanoislands, namely the conical and pyramidal ones with different heights. Two slopes in emission current-voltage characteristics in Fowler-Nordheim coordinates were observed and is explained by emission from different SiGe nanoislands. The increase of emission current and decrease the slope of curve in F-N coordinates under green light illumination has been revealed. The model of electron field emission and photoemission from SiGe nanoislands based on energy band diagram of Si-Ge heterostructure has been proposed.