Laser CVD Growth of Uniquely -oriented β-Ga2 O3 Films on Quartz Substrate with Ultrafast Photoelectric Response.

Abstract

The oriented growth of β-Ga2 O3 films has triggered extensive interest due to the remarkable and complex anisotropy found in the β-Ga2 O3 bulks. Remarkable properties, including stronger solar-blind ultraviolet (SBUV) absorption, better mobility, and higher thermal conductivity, are usually observed along <010> direction as compared to other low-index axes. So far, <010>-oriented β-Ga2 O3 film growth has been hindered by the lack of suitable substrates and higher surface energy of the (010) crystal plane. Herein, the first growth of uniquely <010>-oriented β-Ga2 O3 films on quartz substrates by laser chemical vapor deposition (LCVD) are reported. By investigating the effects of deposition temperature (Tdep ) and O2 flow rate (RO2 ) on the growth of β-Ga2 O3 films, it is found that the formation of <010> orientation is closely related to the higher stability of oxygen close-packed planes under O-rich condition. As a result, a grain size of up to ≈2µm and a deposition rate of up to ≈ 40µm h-1 are obtained. Metal-semiconductor-metal (MSM) type detector based on <010>-oriented β-Ga2 O3 film exhibits ultra-fast response speed, 1-2 orders of magnitude higher than those of most detectors based on β-Ga2 O3 films with other orientations.