Monolithic integration of rare-earth oxides and semiconductors for on-silicon technology

Abstract

Several concepts of integration of the epitaxial rare-earth oxides into the emerging advanced semiconductor on silicon technology are presented. Germanium grows epitaxially on gadolinium oxide despite lattice mismatch of more than 4%. Additionally, polymorphism of some of the rare-earth oxides allows engineering of their crystal structure from hexagonal to cubic and formation of buffer layers that can be used for growth of germanium on a lattice matched oxide layer. Molecular beam epitaxy and metal organic chemical vapor deposition of gallium nitride on the rare-earth oxide buffer layers on silicon is discussed.

GaN growth on Si with rare-earth oxide distributed Bragg reflector structures

“…The deterioration of the Gd 2 O 3 layer at high temperatures could be explained by its nitridation and the appearance of the characteristic GdN (111) peak. Nitridation occurs when nitrogen diffuses through the Er 2 O 3 layer during the GaN growth process [4]. The weaker thermal stability of Gd 2 O 3 can induce stress in the upper Er 2 O 3 layer, thereby lowering the energy barrier for nitridation.…”

“…4. The exposure of Er 2 O 3 to hydrogen leads to decomposition of the compound [4], so the growth process started with nitrogen as the carrier gas. From the beginning of the low temperature (570 1C) GaN deposition process (stage a), the reflectance started to oscillate due to interference in the as-grown layer.…”

“…Previous studies have shown that the lattice compatibility of erbium oxide with silicon is worse compared with that with gadolinium oxide, which belongs to the same group of rare-earth oxides. However, the structure of gadolinium oxide/silicon heated to temperatures of 1015 1C demonstrates that there is a chemical reaction between gadolinium oxide and silicon, which results in the reduced reflectance of the structure [4]. In the present study, we performed direct investigations and comparisons of two types of rareearth oxide/silicon DBR heterostructures, which were used for growing GaN by metal-organic chemical vapor deposition (MOCVD).…”

“…The rare-earth oxides Gd 2 O 3 , Er 2 O 3 may be an alternative choice in these layers. The excellent dielectric properties, reasonable thermal conductivity, and large differences in the refractive indices between Si and rare-earth oxides suggest their possible application as electric field suppression layers and high reflectance heterostructures [3,4]. Recent advances in the fabrication of rare-earth oxide/silicon distributed Bragg reflectors (DBR) have opened up their potential applications in III-N-based light-emitting devices as reflecting substrates [5].…”

Depth-dependent phase change in Gd2O3 epitaxial layers under ion irradiation

“…As thin (epitaxial) layers grown on silicon, they represent, intrinsically or after doping, possible high-k (dielectric constant) gate dielectrics for modern metal-oxide-semiconductor devices [8]. They can also be buffers for growth of alternative semiconductors, the choice of which depends on the phase of the REO layer underneath [9]; regarding the REO phase, it has also been shown in GO that the monoclinic structure has a higher k value than its cubic counterpart [10]. In the case of these microelectronics applications, designing layers with control over composition, dopant concentration and crystallographic structure would be highly desirable for high-performance devices.…”