Electrical characterization of Si-doped n-type α-Ga2O3 on sapphire substrates

Abstract

Issues on tin (Sn) doping in the mist chemical vapor deposition of α-Ga2O3 was attributed to conversion of ionization states of Sn from Sn4+ to Sn2+ and/or out-diffusion of Sn after thermal annealing, resulting in highly resistive films. Silicon (Si) doping, instead, was succeeded by the use of a novel doping source of chloro-(3-cyanopropyl)-dimethylsilane [ClSi(CH3)2((CH2)2CN)]. Si was uniformly incorporated in the α-Ga2O3 films and the electrical properties were stable even after the thermal annealing. The activation ratio as donors was nearly 100%. The carrier (electron) concentration was controlled to the level of 1018 cm-3 by the [Si]/[Ga] ratio in the source solution. The maximum mobility was 31.5 cm2/V⋅s, in contrast to 24 cm2/V⋅s with Sn doping, suggesting advantage of Si doping . However, the reduction in dislocation defects in the α-Ga2O3 films formed owing to heteroepitaxy on sapphire was suggested to be the important subject to be considered in the next stage.

Strain states and relaxation for $$\alpha$$-(Al$$_x$$Ga$$_{1-x}$$)$$_2$$O$$_3$$ thin films on prismatic planes of $$\alpha$$-Al$$_2$$O$$_3$$ in the full composition range: Fundamental difference of a- and m-epitaxial planes in the manifestation of shear strain and lattice tilt

“…Additionally, it can be grown heteroepitaxially with high quality on costeffective isostructural α-Al 2 O 3 substrates [17][18][19][20][21][22] (sapphire). It can be doped n-type utilizing, e.g., Si, Sn or F as dopants [22][23][24][25][26] and due to it being isostructural to α-Al 2 O 3 the full compositional range of α-(Al x Ga 1−x ) 2 O 3 from Ga 2 O 3 to Al 2 O 3 can be covered without miscibility gaps allowing bandgap engineering for HEMT structures or quantum wells from 5.3 eV to 8.8 eV [22,[27][28][29][30][31][32][33]. In most reports, α-Ga 2 O 3 and α-(Al x Ga 1−x ) 2 O 3 is grown on the basal c-plane of α-Al 2 O 3 [9, 17-22, 24, 28, 29, 34, 35].…”

Analysis of Deep Traps in Mist Chemical Vapor Deposition‐Grown n‐Type α‐Ga2O3 by Photocapacitance Method

“…Mist CVD is one of the most successful methods for growth and making devices of α-Ga 2 O 3 . [10,[42][43][44] The reason why an m-plane sapphire was used is that mobility in m-plane α-Ga 2 O 3 is reported to be higher than that in c-plane α-Ga 2 O 3 . [42,44] The schematic of the sample is shown in the inset of Figure 1.…”

“…[10,[42][43][44] The reason why an m-plane sapphire was used is that mobility in m-plane α-Ga 2 O 3 is reported to be higher than that in c-plane α-Ga 2 O 3 . [42,44] The schematic of the sample is shown in the inset of Figure 1. The sample is composed of n À and n þ α-Ga 2 O 3 epitaxial layers on an m-plane sapphire substrate by mist CVD.…”

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

“…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.…”