  In this paper, we have demonstrated the large-size free-standing
single-crystal b-Ga2O3 NMs fabricated by the hydrogen implantation and lift-off
process directly from MOCVD grown b-Ga2O3 epifilms on native substrates. The
optimum implantation conditions were simulated with a Monte-Carlo simulation to
obtain the high hydrogen concentration with a narrow ion distribution at the
desired depth. Two as grown b-Ga2O3 samples with different orientation ([100]
and [001]) were used and successfully create 1.2 um thick b-Ga2O3 NMs without
any physical damages. These b-Ga2O3 NMs were then transfer-printed onto rigid
and flexible substrates such as SiC substrate and polyimide substrate. Various
material characterizations were performed to investigate the crystal quality,
surface morphology, optical property, mechanical property, and bandgap before
and after the lift-off and revealed that good material quality is maintained.
This result offers several benefits in that the thickness, doping, and size of
b-Ga2O3 NMs can be fully controlled. Moreover, more advanced b-Ga2O3-based NM
structures such as (AlxGa1-x)2O3/Ga2O3 heterostructure NMs can be directly
created from their bulk epitaxy substrates thus this result provides a viable
route for the realization of high performance b-Ga2O3 NM-based electronics and
optoelectronics that can be built on various substrates and platforms.
