Conductivity control of Sn-doped α-Ga₂O₃ thin films grown on sapphire substrates

Abstract

We achieved the successful fabrication of Sn-doped α-Ga 2 O 3 thin films with higher electron mobility and wider conductivity controls by improving the crystal quality. α-Ga 2 O 3 films showed n-type conductivity with a maximum electron mobility of 24 cm 2 V %1 s %1 . The carrier concentration was successfully controlled in the range of 10 17 -10 19 cm %3 . Crystal defects such as dislocations severely compensate the free carriers in α-Ga 2 O 3 films and restrict the mobility at low carrier concentrations. Therefore, to achieve further conductivity control and higher mobility, improving the crystallinity of α-Ga 2 O 3 films is necessary.

Electrical Properties of Sn‐Doped α‐Ga2O3 Films on m‐Plane Sapphire Substrates Grown by Mist Chemical Vapor Deposition

“…Figure a shows carrier concentration in α‐Ga 2 O 3 films at room temperature as a function of Sn/Ga concentration in source and Figure b shows the relationship between Hall mobility and carrier concentration at room temperature in α‐Ga 2 O 3 films grown on m‐plane sapphire. In Figure b, we also show our previous results of films on c‐plane sapphire reported by Akaiwa et al for comparison. As shown in Figure a, carrier concentrations were almost proportionally varied with the change of Sn/Ga concentration ratio, indicating successful control of carrier concentration.…”

“…FWHM values of XRD ω‐scan profiles of α‐Ga 2 O 3 films grown by two‐step growth procedure were as low as 1200 arcsec for both symmetric plane diffraction and asymmetric plane diffraction. In contrast, as for α‐Ga 2 O 3 films on c‐plane sapphire in our previous report, FWHM values of XRD ω‐scan profiles were around 30 arcsec for symmetric plane diffraction and 1000 arcsec for asymmetric plane diffraction. Therefore, because of larger FWHM values for both symmetric and asymmetric plane diffractions, crystallinities of α‐Ga 2 O 3 films on m‐plane sapphire were inferior than those of films on c‐plane sapphire.…”

“…In addition, the use of sapphire substrates is advantageous because they are available at low cost. We previously reported the successful n‐type doping of α‐Ga 2 O 3 films grown on c‐plane sapphire by Sn‐doping . However, the electron mobility of α‐Ga 2 O 3 films in these reports was as low as 24 cm 2 (V s) −1 .…”

Толстые слои alpha-Ga-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- на сапфировых подложках, полученные методом хлоридной эпитаксии

“…85 эВ для β-фазы и E g ≈ 4.7−4.9 эВ для ε-фазы [1,3]. При легировании оловом и кремнием в α-Ga 2 O 3 наблюдается заметная электронная электропроводность [4], что делает материал особенно привлекательным для УФ полупроводниковых приборов. Объемные монокристаллы α-Ga 2 O 3 не могут быть получены традиционными методами кристаллизации из расплава.…”

“…Объемные монокристаллы α-Ga 2 O 3 не могут быть получены традиционными методами кристаллизации из расплава. Монокристаллические слои α-Ga 2 O 3 могут быть получены только различными эпитаксиальными методами [4][5][6][7][8][9][10][11][12][13]. Следует отметить, что α-Ga 2 O 3 , являясь метастабильной фазой, в процессе роста, т. е. при увеличении толщины слоя, может переходить в другие фазы.…”