Threshold fluence measurement for laser liftoff of InP thin films by selective absorption

A. Jan, B.A. Reeves, Y.B. Van De Burgt, G.J. Hayes, B.M. Clemens

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review


We explore conditions for achieving laser liftoff in epitaxially grown heterojunctions, in which single crystal thin films can be separated from their growth substrates using a selectively absorbing buried intermediate layer. Because this highly non-linear process is subject to a variety of process instabilities, it is essential to accurately characterize the parameters resulting in liftoff. Here, we present an InP/InGaAs/InP heterojunction as a model system for such characterization. We show separation of InP thin films from single crystal InP growth substrates, wherein a ≈10 ns, Nd:YAG laser pulse selectively heats a coherently strained, buried InGaAs layer. We develop a technique to measure liftoff threshold fluences within an inhomogeneous laser spatial profile, and apply this technique to determine threshold fluences of the order 0.5 J cm −2 for our specimens. We find that the fluence at the InGaAs layer is limited by non-linear absorption and InP surface damage at high powers, and measure the energy transmission in an InP substrate from 0 to 8 J cm −2. Characterization of the ejected thin films shows crack-free, single crystal InP. Finally, we present evidence that the hot InGaAs initiates a liquid phase front that travels into the InP substrate during liftoff.

Originele taal-2Engels
Aantal pagina's7
TijdschriftAdvanced Engineering Materials
Nummer van het tijdschrift1
Vroegere onlinedatum11 sep 2017
StatusGepubliceerd - 1 jan 2018


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