Ge-Doped ${\beta }$ -Ga2O3 MOSFETs

Ultrawide‐Bandgap Semiconductors: Research Opportunities and Challenges

“…The projection uses the experimentally derived E C for GaN [59] as the baseline (corrected for the updated values of mobility and permittivity in the table), as this is the highest known E C for any GaN or SiC diode. These projections follow the method described in detail in Hollis and Kaplar, [60] and, to ensure a level playing field for all materials, [29,54] n (Si) below 80-85% Al; p (Mg deep) [54,97] ; polarization doping [355,356] Possible S donor [97] ; no good acceptor Polarization-induced 2DEG n type (Sn, Si, Ge donors) [357] ; no known acceptor n type (S donor); deep acceptors [98] Light to medium p type for N A < mid- [106,107] 2018: 38 mm. [105] 2018: 38 mm.…”

“…It has available donors (Sn, Si, Ge), [357] but no acceptors. Possibly its greatest advantage is the availability of reasonably-sized substrates, thanks to the growth technologies described in Section 2.3.…”

Deep level defects in Ge-doped (010) β-Ga2O3 layers grown by plasma-assisted molecular beam epitaxy

“…[1][2][3][4][5][6][7][8][9][10][11] Interest is also rising for possible applications as a deep ultraviolet solar blind detector due to its outstanding transparency out to $260 nm. 10,11 However, perhaps the primary driver for the interest is that b-Ga 2 O 3 , with its $4.5-4.9 eV bandgap, 2 is available as a bulk crystal, and therefore, native substrates are available for lattice-matched epitaxial growth of device structures, unlike contemporary wide and ultrawide bandgap semiconductors.…”

“…10,11 However, perhaps the primary driver for the interest is that b-Ga 2 O 3 , with its $4.5-4.9 eV bandgap, 2 is available as a bulk crystal, and therefore, native substrates are available for lattice-matched epitaxial growth of device structures, unlike contemporary wide and ultrawide bandgap semiconductors. In spite of the early stage of development, promising device demonstrations have already been reported, including metal-semiconductor field effect transistors (MESFETs), 1 metal-oxide field effect transistors (MOSFETs), [2][3][4][5] Schottky diodes, [6][7][8][9] FinFETs, 12 delta-doped FETs, 13 and (Al 1-x Ga x ) 2 O 3 /Ga 2 O 3 modulation-doped field effect transistors (MODFETs) grown by plasma-assisted molecular beam epitaxy (PAMBE). 14,15 For these devices to evolve as theoretically predicted, controlled doping during epitaxy is critical and doping studies in b-Ga 2 O 3 are at an early stage for molecular beam epitaxy (MBE) growth.…”

“…17 In addition, Ge 4þ is predicted to preferentially incorporate on the tetrahedral Ga(I) site, making it a potentially more effective dopant than Sn 4þ which favors the octahedrally coordinated Ga(II) site. 3,16 Moreover, the much higher vapor pressure of Ge oxides compared with Si oxides avoids source oxidation, 17,18 and a wide range of controllable electron concentrations (10 16 -10 20 cm À3 ) for Ge-doped b-Ga 2 O 3 has been demonstrated. 19 Coupling these observations with the successful demonstrations of Ge-doped PAMBE-grown b-Ga 2 O 3 MOSFETs 3 and (Al 1-x Ga x ) 2 O 3 /Ga 2 O 3 MODFETs 14 implies that Ge might become the dopant of choice for bGa 2 O 3 devices.…”