Demonstration of Confined Electron Gas and Steep-Slope Behavior in Delta-Doped GaAs-AlGaAs Core–Shell Nanowire Transistors

Abstract

Strong surface and impurity scattering in III-V semiconductor-based nanowires (NW) degrade the performance of electronic devices, requiring refined concepts for controlling charge carrier conductivity. Here, we demonstrate remote Si delta (δ)-doping of radial GaAs-AlGaAs core-shell NWs that unambiguously exhibit a strongly confined electron gas with enhanced low-temperature field-effect mobilities up to 5 × 10(3) cm(2) V(-1) s(-1). The spatial separation between the high-mobility free electron gas at the NW core-shell interface and the Si dopants in the shell is directly verified by atom probe tomographic (APT) analysis, band-profile calculations, and transport characterization in advanced field-effect transistor (FET) geometries, demonstrating powerful control over the free electron gas density and conductivity. Multigated NW-FETs allow us to spatially resolve channel width- and crystal phase-dependent variations in electron gas density and mobility along single NW-FETs. Notably, dc output and transfer characteristics of these n-type depletion mode NW-FETs reveal excellent drain current saturation and record low subthreshold slopes of 70 mV/dec at on/off ratios >10(4)-10(5) at room temperature.

Near-thermal limit gating in heavily doped III-V semiconductor nanowires using polymer electrolytes

“…The PE gate gives very strong gating with sub-threshold swing S ∼ 75±15 mV/dec and on-off ratio near 10 4 . The sub-threshold swing is comparable to the best obtained for n-InP (68 mV/dec) [5] and n-GaAs (70 mV/dec) [7] nanowire MOSFETs and within 25% of the room temperature thermal limit (60 mV/dec). We obtain on-current I on ∼ 0.25 µA at V sd = 100 mV corresponding to 400 kΩ channel resistance, with contact resistance R on ∼ 30 kΩ previously measured for this doping level [12].…”

In situpassivation of GaAsP nanowires

“…The absence of catalyst and the low substrate temperature are favorable to radial growth and thus enable the shell formation. 21,22 For the GaAsP shell case, the As cracker temperature was also increased to ~900°C, in order to crack As 4 into As 2 molecules which was shown to enhance the lateral deposition. 29 After stabilizing the substrate temperature, the Ga(As)P shell was deposited by opening the Ga, As, and P shutters simultaneously.…”

Alloy Fluctuations Act as Quantum Dot-like Emitters in GaAs-AlGaAs Core–Shell Nanowires

“…1 Since GaAs-AlGaAs heterostructures were realized in nanowire form, 2,3 they have been explored as potential components for ultrasmall, high performance devices including high-electron mobility transistors, 4 lasers, 5,6 and light-emitting diodes. 7,8 This is mainly due to the unique one-dimensional geometry of nanowires, which facilitates formation of radial and axial heterostructures and direct incorporation into Si based devices.…”