Probing crystallographic orientation-specific carrier lifetimes in epitaxial Ge/AlAs and InGaAs/InP heterostructures

Abstract

Current silicon (Si) fin transistor relies on (100) and (110) crystallographic oriented surfaces, and the proposed alternate channel transistor technology comprises of material with higher mobility than Si. Crystallographically oriented...

Interplay Between Strain and Thickness on the Effective Carrier Lifetime of Buffer-Mediated Epitaxial Germanium Probed by the Photoconductance Decay Technique

“…Figure b shows 1/τ eff plotted against 2/ d , which yielded values of ∼114 ± 2 ns and ∼21.3 ± 0.04 cm/s for τ bulk and S , respectively. We recently reported an effective lifetime of >100 ns on unstrained epitaxial Ge grown on a III–V buffer template in our previous work as well . The condition of S ≪ 2D/ d is readily satisfied in this case, considering D ≈ 9 cm 2 /s, extracted from Hall measurements (not shown here), which enables the determination of τ bulk from eq .…”

“…We recently reported an effective lifetime of >100 ns on unstrained epitaxial Ge grown on a III−V buffer template in our previous work as well. 48 The condition of S ≪ 2D/d is readily satisfied in this case, considering D ≈ 9 cm 2 /s, extracted from Hall measurements (not shown here), which enables the determination of τ bulk from eq 3. Discussion regarding the accuracy of S following from ref 49 for the condition of Sd/D < 0.25, which is satisfied in this case, indicates that the extracted S value is accurate to within 4% over the entire range of S values.…”

Carrier Recombination Dynamics of Surface-Passivated Epitaxial (100)Ge, (110)Ge, and (111)Ge Layers by Atomic Layer Deposited Al2O3

“…It was believed to be the defect states within the bulk responsible for the low carrier lifetime for the (111)Ge plane. In addition, it was also not clear whether the surface states or metallic nature of this crystal plane is responsible for the low carrier lifetime from this study . However, the different surface trap states were reported within the Si and Ge − semiconductors, and the density of the surface states ( N SS ) in Ge related to its crystallographic orientations varies as N SS ⟨111⟩ < N SS ⟨110⟩ < N SS ⟨100⟩. , However, the (111)Ge surface exhibited high electrical conductivity leading to short carrier lifetime compared to other orientations. − If the (111)Ge surface is passivated with ALD Al 2 O 3 , where trimethylaluminum (TMA, Al­(CH 3 ) 3 ) was used as the metal precursor, then the carrier lifetime should improve from the passivated Al 2 O 3 /(111)Ge heterostructure along with other orientations.…”

“…In addition, it was also not clear whether the surface states or metallic nature of this crystal plane is responsible for the low carrier lifetime from this study. 50 However, the different surface trap states were reported within the Si 52 and Ge 53−55 semiconductors, and the density of the surface states (N SS ) in Ge related to its crystallographic orientations varies as N SS ⟨111⟩ < N SS ⟨110⟩ < N SS ⟨100⟩. 53,55 However, the (111)Ge surface exhibited high electrical conductivity leading to short carrier lifetime compared to other orientations.…”

“…The man-made (100) and (110) or naturally occurring crystal surfaces can exhibit different electronic and photonic properties − with different carrier lifetimes on those surfaces. The carrier recombination properties from the crystallographically oriented (100)­Ge, (110)­Ge, and (111)Ge were demonstrated, ,, where the (111)Ge surface exhibited a low carrier lifetime compared to other orientations. It was believed to be the defect states within the bulk responsible for the low carrier lifetime for the (111)Ge plane.…”