Laser CVD Growth of Uniquely <010>‐oriented β‐Ga₂O₃ Films on Quartz Substrate with Ultrafast Photoelectric Response

Abstract

The oriented growth of β‐Ga2O3 films has triggered extensive interest due to the remarkable and complex anisotropy found in the β‐Ga2O3 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‐Ga2O3 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‐Ga2O3 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‐Ga2O3 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‐Ga2O3 film exhibits ultra‐fast response speed, 1–2 orders of magnitude higher than those of most detectors based on β‐Ga2O3 films with other orientations.

High-Performance Solar-Blind Photodetector Based on (010)-Plane β-Ga2O3 Thermally Oxidized from Nonpolar (110)-Plane GaN

“…38,39 Here, the lattice mismatch is defined as δ = (a epi − a sub )/a sub , where a epi and a sub represent the lattice parameters of the epitaxial layer and the substrate, respectively. As shown in panels a and d of Figure 3, the surface morphology of (010)-plane β-Ga 2 O 3 samples T 1.5 and T 3 exhibits a three-dimensional (3D)-structured roof-like feature, which is similar to the (010)-plane results reported by Tu et al 22 but differs from both the (−201)-plane results reported by Tang et al 40 and the SEM surface image of comparison sample T C6 (see Figure S4 of the Supporting Information). As shown in panels b, c, e, and f of Figure 3, the cross-sectional SEM images and energy-dispersive X-ray spectrometry (EDS) mapping images for samples T 1.5 and T 3 were measured and their layer structures were determined from the measurement procedure and EDS mapping images.…”

“…However, the growth of (010)-plane β-Ga 2 O 3 is challenging as a result of its higher surface energy rather than other planes and the lack of a suitable substrate with a small lattice mismatch with (010)plane β-Ga 2 O 3 . 22 In this study, (010)-plane β-Ga 2 O 3 was successfully thermally oxidized using nonpolar (110) a-plane GaN for the first time. Its structural properties were characterized by Xray diffraction (XRD) and scanning electron microscopy (SEM).…”

“…19 Among them, β-Ga 2 O 3 shows increasing interest from the scientific community as a result of its exclusive thermodynamically stable structure. 1 Recent studies have shown excellent performance of β-Ga 2 O 3based SBPDs with high responsivity, 4,20 high sensitivity, 21 and fast response, 12,22 as a result of their high ultraviolet (UV) transmittance, economic efficiency, radiation resistance, and thermal and chemical stability. This means that β-Ga Ga 2 O 3 includes the Czochralski method, vertical Bridgman growth method, floating zone growth method, and various epitaxial growth methods.…”

“…On the other hand, (010)-plane β-Ga 2 O 3 exhibited a larger thermal conductivity, higher UV absorption coefficient, higher mobility, and larger Schottky barrier heights rather than other crystal planes of β-Ga 2 O 3 . ,, In this context, the SBPDs fabricated on the basis of (010)-plane β-Ga 2 O 3 allow for better heat dissipation, stronger solar-blind UV absorption, faster response, and lower dark current. However, the growth of (010)-plane β-Ga 2 O 3 is challenging as a result of its higher surface energy rather than other planes and the lack of a suitable substrate with a small lattice mismatch with (010)-plane β-Ga 2 O 3 …”