Laser CVD Growth of Uniquely <010>-oriented β-Ga 2 O 3 Films on Quartz Substrate with Ultrafast Photoelectric Response.

The oriented growth of β-Ga 2 O 3 films has triggered extensive interest due to the remarkable and complex anisotropy found in the β-Ga 2 O 3 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-Ga 2 O 3 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-Ga 2 O 3 films on quartz substrates by laser chemical vapor deposition (LCVD) are reported. By investigating the effects of deposition temperature (T dep ) and O 2 flow rate (R O2 ) on the growth of β-Ga 2 O 3 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 ≈2 µm and a deposition rate of up to ≈ 40 µm h -1 are obtained. Metal-semiconductor-metal (MSM) type detector based on <010>-oriented β-Ga 2 O 3 film exhibits ultra-fast response speed, 1-2 orders of magnitude higher than those of most detectors based on β-Ga 2 O 3 films with other orientations.