Low temperature synthesis of highly oriented p-type Si1-xGex (x: 0–1) on an insulator by Al-induced layer exchange

Abstract

A composition tunable Si 1-x Ge x alloy has a wide range of applications, including in electronic and photonic devices. We investigate the Al-induced layer exchange (ALILE) growth of amorphous Si 1-x Ge x on an insulator. The ALILE allowed Si 1-x Ge x to be large grained (> 50 lm) and highly (111)-oriented (> 95%) over the whole composition range by controlling the growth temperature (400 C). From a comparison with conventional solid-phase crystallization, we determined that such characteristics of the ALILE arose from the low activation energy of nucleation and the high frequency factor of lateral growth. The Si 1-x Ge x layers were highly p-type doped, whereas the process temperatures were low, thanks to the electrically activated Al atoms with the amount of solid solubility limit. The electrical conductivities approached those of bulk single crystals within one order of magnitude. The resulting Si 1-x Ge x layer on an insulator is useful not only for advanced SiGe-based devices but also for virtual substrates, allowing other materials to be integrated on threedimensional integrated circuits, glass, and even a plastic substrate.

High-Electrical-Conductivity Multilayer Graphene Formed by Layer Exchange with Controlled Thickness and Interlayer

“…Metal-induced layer exchange (MILE) has been actively studied in the field of group-IV semiconductors, including Si 27–31 , Ge 32–37 , and SiGe 38,39 . In MILE, an amorphous semiconductor layer crystallizes through “layer exchange” between the amorphous layer and a catalyst metal layer.…”

High-hole mobility Si1-Ge (0.1 ≤ x ≤ 1) on an insulator formed by advanced solid-phase crystallization

“…20 This is attributed to the difference in the activation energies of Si and Ge required for nucleation and growth. 21,30 Here, we observed that large grains can be obtained even for Ge-rich SiGe by controlling Td. The window at which Td has an effect of increasing the grain size narrows as x increases, though x = 0.1 does not follow this trend.…”

“…11,12 A large number of SGOI-forming methods have been developed: layer transfer, 13 Ge condensation, 4,[14][15][16] laser annealing, 7,10 rapid-melting growth, 8,12 chemical-vapor deposition (CVD), 2,17,18 sputtering, 9 solid-phase crystallization (SPC), 3,[19][20][21][22] and metal-induced crystallization 23,24 including layer exchange. [25][26][27][28][29][30] Despite the variety of methodologies, it is still difficult to obtain a large-area SGOI with excellent crystallinity and electrical characteristics by a simple method, suitable for practical applications.…”

“…3 In recent years, the SPC of a-Ge has been actively investigated. [30][31][32][33][34][35][36] Very recently, we have dramatically improved the hole mobility of SPC-Ge from 140 to 340 cm 2 /Vs by controlling the deposition temperature of an a-Ge precursor. 37 Furthermore, we achieved a Ge hole mobility of 450 cm 2 /Vs by thickening the Ge film and post-annealing at 500 °C.…”

Minority carrier lifetime of Ge film epitaxial grown on a large-grain seed layer on glass

“…In line with this, the low-temperature synthesis of polycrystalline (poly-) Ge on glass has been investigated using solid-phase crystallization (SPC) [9][10][11], sputtering [12], and chemical vapor deposition (CVD) [13,14]. Metal-induced layer exchange, using Al [15][16][17][18][19], Au [20,21], and Ag [22,23] as catalysts, is a unique method that significantly lowers the crystallization temperature of amorphous (a-) Ge (≤ 350 °C). In particular, Al-induced layer exchange (ALILE) allows for large-grained (> 50 µm), (111)-oriented, and highly p-doped Ge thin films (thickness: 50 nm) [18,19], which will be useful as a seed layer for a thick (> 500 nm) light absorbing layer.…”