Paramorphic Growth: A New Approach in Mismatched Heteroepitaxy to Prepare Fully Relaxed Materials

Abstract

We propose paramorphic growth as a new approach for growing thick, ideally relaxed, epitaxial layers on mismatched substrates. First, a thin seed layer, originally grown pseudomorphically strained on a mismatched substrate coated with a sacrificial layer, is separated by chemical etching from its original substrate and subsequently deposited on the final substrate after being elastically relaxed. Consequently, thick layers, lattice matched to the cubic-relaxed seed layer, can be grown epitaxially without the introduction of any structural defects. The validity of this approach is demonstrated by growing fully relaxed In0.65Ga0.35As thick layers on 300×300 µm2 platforms deposited on an InP substrate, using molecular beam epitaxy.

Wafer‐Scale Strain Engineering of Ultrathin Semiconductor Crystalline Layers

“…Additionally, heat treatments over 400 °C cannot be performed for III‐V semiconductor compound films without plastic deformation of the alloy films. In a separate experiment, relaxation of InGaAs strained regions was achieved in selectively etched mesas that allowed very small areas of the film (300 μm × 300 μm) to relax 12–14. Although the film relaxes, it is trapped between other mesas, limiting its applicability to device fabrication.…”

Elastically relaxed free-standing strained-silicon nanomembranes

“…Elastically strain relaxed InGaAs regions have been made starting with mesas that were subsequently undercut, allowing the relaxed InGaAs tethered regions to fall to the substrate below to create areas of relaxed material. 15,16 We describe here a methodology that extends the above approaches in that it allows the fabrication of large freestanding elastically strain-relaxed membranes. In our case the membranes are SiGe based, but the concept is generalizable.…”

Growth and characterization of totally relaxed InGaAs thick layers on strain-relaxed paramorphic InP substrates

“…6a). 5 In contrast, a classical cross-hatched morphology is observed for In 0.65 Ga 0.35 As grown simultaneously on unprocessed reference areas of the bulk InP substrate (Fig. 6b).…”

“…5 However, this process was only limited to relatively small areas of a few 100 µm 2 . We have demonstrated the validity of this so-called "paramorphic approach" by growing thick In 0.65 Ga 0.35 As layers on 50 ϫ 50 µm 2 In 0.65 Ga 0.35 As and InAs 0.25 P 0.75 seed platforms, 0.81% mismatched to InP.…”