Delta-doped β-gallium oxide field-effect transistor

Abstract

We report silicon delta doping in Gallium Oxide (β-Ga 2 O 3 ) grown by plasma assisted molecular beam epitaxy using a shutter pulsing technique. We describe growth procedures that can be used to realize high Si incorporation in an oxidizing oxygen plasma environment. Delta doping was used to realize thin (12 nm) low-resistance layers with sheet resistance of 320Ohm/square (mobility of 83 cm 2 /Vs, integrated sheet charge of 2.4x10 14 cm -2 ). A single deltadoped sheet of carriers was employed as a channel to realize a field effect transistor with current I D,MAX =292 mA/mm and transconductance g M = 27 mS/mm.

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

“…16 For Si-doping, growth of uniformly doped thick layers by PAMBE is challenged by Si source oxidation in the oxygen plasma environment, creating a self-limiting process. 13 The other two candidates, Ge 4þ and Sn 4þ , are identified as a better match with Ga 3þ cationic size. 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.…”

“…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.…”

Recent Advances in β-Ga2O3–Metal Contacts

“…Hence, to avoid the degradation of contact characteristics at elevated annealing temperature, more complex metal stacks should be adopted. By far, Ti/Al/Au [50, 52], Ti/Au/Ni [61, 62], and Ti/Al/Ni/Au metal stacks [13, 21, 63, 64] have been employed to form electrical contacts on β-Ga 2 O 3 . But a comprehensive comparison of contact characteristics between these metal stacks is still insufficient.…”

Enhancement‐Mode β‐Ga2O3 Metal‐Oxide‐Semiconductor Field‐Effect Transistor with High Breakdown Voltage over 3000 V Realized by Oxygen Annealing

“…Although β ‐Ga 2 O 3 is a semiconductor with ultrawide bandgap, n‐type doping could be easily achieved with Si, Ge, or Sn acting as shallow donors . Depletion‐mode (D‐mode) β ‐Ga 2 O 3 metal‐oxide‐semiconductor field‐effect transistors (MOSFETs) have been reported with high current density, high breakdown voltage, and high power figure of merit (PFOM) .…”

“…Although β-Ga 2 O 3 is a semiconductor with ultrawide bandgap, n-type doping could be easily achieved with Si, Ge, or Sn acting as shallow donors. [4][5][6] Depletion-mode (D-mode) β-Ga 2 O 3 metaloxide-semiconductor field-effect transistors (MOSFETs) have been reported with high current density, high breakdown voltage, and high power figure of merit (PFOM). [7][8][9][10][11] However, due to the lack of effective p-type doping, the high-voltage enhancement-mode (E-mode) operation is comparatively difficult to be achieved.…”