Highly conductive homoepitaxial Si-doped Ga2O3 films on (010) β-Ga2O3 by pulsed laser deposition

Abstract

Si-doped Ga2O3 thin films were fabricated by pulsed laser deposition on semi-insulating (010) β-Ga2O3 and (0001) Al2O3 substrates. Films deposited on β-Ga2O3 showed single crystal, homoepitaxial growth as determined by high resolution transmission electron microscopy and x-ray diffraction. Corresponding films deposited on Al2O3 were mostly single phase, polycrystalline β-Ga2O3 with a preferred (201¯) orientation. An average conductivity of 732 S cm−1 with a mobility of 26.5 cm2 V−1 s−1 and a carrier concentration of 1.74 × 1020 cm−3 was achieved for films deposited at 550 °C on β-Ga2O3 substrates as determined by Hall-Effect measurements. Two orders of magnitude improvement in conductivity were measured using native substrates versus Al2O3. A high activation efficiency was obtained in the as-deposited condition. The high carrier concentration Ga2O3 thin films achieved by pulsed laser deposition enable application as a low resistance ohmic contact layer in β-Ga2O3 devices.

Valence and conduction band offsets of β-Ga2O3/AlN heterojunction

“…2(a), we notice that besides the substrate diffraction peaks at 36.1 and 41.1 from (0002) AlN and c-plane sapphire substrate, there are three other peaks at 18.9 , 38.3 , and 59.1 which corresponds to (À201), (À402), and (À603) planes of b-Ga 2 O 3 , respectively. 24 Figure 2(b) displays the micro-Raman spectra, confirming the b-Ga 2 O 3 layer on AlN/ sapphire by observing the Raman peaks at 168 and 201 cm À1 where the phonon modes are in good agreement with the previous report. 25 These two peaks are not observed in sample C due to the extreme thin b-Ga 2 O 3 layer ($1.5 nm).…”

High‐Quality Si‐Doped β‐Ga2O3 Films on Sapphire Fabricated by Pulsed Laser Deposition

“…PLD of Ga 2 O 3 has been demonstrated previously and most of these early references primarily investigate the material quality of β-Ga 2 O 3 deposited on Al 2 O 3 . [3][4][5][6] Later, pulsed laser deposited β-Ga 2 O 3 on Al 2 O 3 has also been used for demonstrating device applications, such as solar-blind UV detectors [7,8] and Schottky diodes, for instance, with Cu, [9] Ni, [10] and Ir [11] contacts. Silicon, a common impurity in Ga 2 O 3 grown from melt, has been shown to be acting as a donor and contribute to the n-type character of substrates, presumably residing on substitutional Ga sites.…”

Epitaxial growth of β-Ga2O3 thin films on Ga2O3 and Al2O3 substrates by using pulsed laser deposition

“…In recent years, various methods of growth have been used for epitaxial growth of Ga 2 O 3 films, for example, metal organic chemical vapor deposition (MOCVD), 6 RF magnetron sputtering, 7 chemical vapor deposition (CVD), 8 atomic layer deposition (ALD), 9 molecular beam epitaxy (MBE) 10,11 and pulsed laser deposition (PLD). [12][13][14] Among them, PLD technique has many advantages for oxide film deposition, such as, easy to use, high deposition rate, low growth temperature, and no limit to the types of target material. As for substrates, lattice constant matching and the thermal properties between oxide films and substrates should be considered first.…”