Fabrication of MIS photodetector with Ge nanocrystals grown by MBE

In this paper, it is shown for the first time that Ge nanocrystals (Ge NCs) obtained via solid-state dewetting of amorphous GOI can be used as the active absorbers embedded in a silicon dioxide matrix of metal–insulator–semiconductor photodetectors (MIS PD). The Ge NCs have been obtained by a combination of Ge deposition by molecular beam epitaxy (MBE) on tunnel thermal silicon oxide and solid-state dewetting processes. The structural and morphology characterizations performed using high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) show that the Ge NCs embedded in SiO2 of MIS PD are monocrystalline, homogeneous and have well-defined shape and high density suitable for optoelectronic applications. The I–V and photocurrent measurements performed on these innovative structures show that the Ge NCs contribute efficiently in the electrical transport by increasing the current density via creating an intermediate conduction step in the MIS structure and enhance the photocurrent via photogeneration of new carriers. We have observed that for the structure with Ge NCs, the photocurrent increases 10 times at reverse bias Vg = − 1 V when it is illuminated. These results indicate that the crystalline Ge NCs obtained via solid-state dewetting can be integrated with optoelectronics and photonics technologies to produce new high-performance optoelectronic devices fully compatible with complementary oxide metal (CMOS) technology.