Surface dynamics in III-V epitaxy and its device implications

Metalorganic vapour phase epitaxy (MOVPE) is a well-established, industry-compatible, compound semiconductor crystal growth technique, allowing for efficient and controllable material deposition. A wide range of semiconductor devices, both from III-V and nitrides families, are commonly fabricated for a broad range of applications in photonics, electronics and related fields, due to the reproducibility, scalability and overall excellent control over the growth process. Nevertheless, despite the technique’s popularity, there persists a large number of unresolved issues (mostly related to growth process/dynamic understanding) effectively hindering some of potential developments of III-V devices. A major unresolved technological issue, is the reported long range “leakage” of the dopant Zn into intrinsic layers during (and post) epitaxy, including the device processing steps. Zn is used as a typical p-type dopant for III-V materials and devices, but it is reportedly highly diffusive and historically very problematic. To bypass the Zn related problems, the large majority of InP based photonic devices, such as lasers and modulators, are fabricated with an n-i-p design, using p-type dopant at the top of the device. This approach essentially limits the design degree of freedom and stands in the way of the novel advanced stacked device architectures. This work reevaluated the Zn doping issues with unprecedented and surprising findings on Zn dopant behavior. The secondary ion mass spectrometry (SIMS) experiments show that Zn (or its precursors) can behave as a surfactant; accumulating on the sample surface during the growth of intentional doping layer and gradually incorporating into the nominally undoped layers even after the Zn source is shut off. Experimental findings are modelled by combining the surfactant and diffusion behavior with good qualitative agreement. Also, we demonstrated that this phenomenology can be suppressed and controlled either by introducing growth interruption steps or, even more effectively, introducing a competing surfactant species (Sb or its precursors). Our results highlight the relevance of (often overlooked) multi-faceted surface processes during MOVPE epitaxy, and help the implementation of robust solutions for novel device designs, crucially enabling next-generation integrated III-V applications.

Grantor dc:publisher

University College Cork

Year dc:date.issued

2024

Author dc:creator

• Ozcan Atar, Ayse

Advisors dc:contributor.advisor

• Pelucchi, Emanuele
• Juska, Gediminas

• MOVPE
• Surfactant
• Zn doping
• SIMS
• III-V

Statement dc:rights

• © 2024, Ayse Ozcan Atar.

Licence dc:rights.uri

• https://creativecommons.org/licenses/by-nc-sa/4.0/

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10468/16428

OAI identifier oai:identifier

oai:cora.ucc.ie:10468/16428