Improved Quantum Dot Stacking for Intermediate Band Solar Cells using Strain Compensation

Paul J. Simmonds, Meng Sun, Ramesh Babu Laghumavarapu, Baolai Liang, Andrew G. Norman, Jun Wei Luo, Diana L. Huffaker

Research output: Contribution to journalArticlepeer-review

16 Scopus Citations


We use thin tensile-strained AlAs layers to manage compressive strain in stacked layers of InAs/AlAsSb quantum dots (QDs). The AlAs layers allow us to reduce residual strain in the QD stacks, suppressing strain-related defects. AlAs layers 2.4 monolayers thick are sufficient to balance the strain in the structures studied, in agreement with theory. Strain balancing improves material quality and helps increase QD uniformity by preventing strain accumulation and ensuring that each layer of InAs experiences the same strain. Stacks of 30 layers of strain-balanced QDs exhibit carrier lifetimes as long as 9.7 ns. QD uniformity is further enhanced by vertical ABAB... ordering of the dots in successive layers. Strain compensated InAs/AlAsSb QD stacks show great promise for intermediate band solar cell applications.

Original languageAmerican English
Article number445402
Number of pages7
Issue number44
StatePublished - 7 Nov 2014

Bibliographical note

Publisher Copyright:
© 2014 IOP Publishing Ltd.

NREL Publication Number

  • NREL/JA-5K00-63346


  • InAs/AlAsSb
  • intermediate band solar cells
  • self-assembled quantum dots
  • strain compensation
  • tensile strain


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