Elucidating the Role of InGaAs and InAlAs Buffers on Carrier Dynamics of Tensile-Strained Ge Double Heterostructures

Shuvodip Bhattacharya, Steven Johnston, Robert Bodnar, Mantu Hudait

Research output: Contribution to journalArticlepeer-review


Extensive research efforts of strained germanium (Ge) are currently underway due to its unique properties, namely, (i) possibility of band gap and strain engineering to achieve a direct band gap, thus exhibiting superior radiative properties, and (ii) higher electron and hole mobilities than Si for upcoming technology nodes. Realizing lasing structures is vital to leveraging the benefits of tensile-strained Ge (..epsilon..-Ge). Here, we use a combination of different analytical tools to elucidate the effect of the underlying InGaAs/InAlAs and InGaAs overlaying heterostructures on the material quality and strain state of ..epsilon..-Ge grown by molecular beam epitaxy. Using X-ray analysis, we show the constancy of tensile strain in sub-50 nm ..epsilon..-Ge in a quantum-well (QW) heterostructure. Further, effective carrier lifetime using photoconductive decay as a function of buffer type exhibited a high (low) defect-limited carrier lifetime of ~68 ns (~13 ns) in 0.61% (0.66%) ..epsilon..-Ge grown on an InGaAs (InAlAs) buffer. These results correspond well with the measured surface roughness of 1.289 nm (6.303 nm), consistent with the surface effect of the ..epsilon..-Ge/III-V heterointerface. Furthermore, a reasonably high effective lifetime of ~78 ns is demonstrated in a QW of ~30 nm 1.6% ..epsilon..-Ge, a moderate reduction from ~99 ns in uncapped ..epsilon..-Ge, alluding to the surface effect of the overlying heterointerface. Thus, the above results highlight the prime quality of ..epsilon..-Ge that can be achieved via III-V heteroepitaxy and paves a path for integrated Ge photonics.
Original languageAmerican English
Pages (from-to)4247-4256
Number of pages10
JournalACS Applied Electronic Materials
Issue number6
StatePublished - 2024

NREL Publication Number

  • NREL/JA-5K00-90326


  • bulk lifetime
  • carrier lifetime
  • germanium
  • molecular beam epitaxy
  • photoconductance
  • surface recombination velocity
  • tensile strain
  • x-ray diffraction


Dive into the research topics of 'Elucidating the Role of InGaAs and InAlAs Buffers on Carrier Dynamics of Tensile-Strained Ge Double Heterostructures'. Together they form a unique fingerprint.

Cite this