Mobility and saturation drift velocity enhancementin highlydoped GaAs and In _x Ga _{1– x} As structures designed for use inpower FET devices

Monte Carlo simulation of electron transport in highly delta-doped GaAs/AlGaAs quantum wells

“…Masselink [7] and Roberts et al [4] have found a clear correlation between µ and v sat for delta-doped quantum wells with different doping profiles. This correlation is very useful since it is essential to increase both quantities for satisfactory FET design.…”

“…However, n channel is limited by the conduction band offset, making these devices less than optimal for the power applications described above. Masselink [2], Schubert and Ploog [3], Roberts et al [4] and Harris et al [5] have shown that delta-doping (where the dopants are confined to a single atomic plane) enables improvements in n channel without a large reduction in v sat . Thus a delta-doped quantum well may have advantages as the conducting channel of a power FET [6], the structure of which is sketched in figure 1.…”

“…In this paper, we have calculated the velocity-field behaviour for electrons in delta-doped GaAs/AlGaAs quantum wells of the type studied by Roberts et al [4]. In particular, we have considered the structure shown in figure 2, in which the delta-doped plane is at a distance Z δ = 5 Å from the surface side of the well.…”

“…In particular, we have considered the structure shown in figure 2, in which the delta-doped plane is at a distance Z δ = 5 Å from the surface side of the well. We have compared the theoretical curves with experimental results from such a sample at 77 K and 300 K, obtained using the velocity-pulse method described in [4]. Our aim was to identify to what extent real-space and K-space transfer affect the high-field results-Masselink [2,7] and Thobel et al [8] have argued that both types of transfer may contribute but there is no conclusion from these references on the extent to which each contributes.…”

Investigation of delta-doped quantum wells for power FET applications

“…Current heterojunction FET designs are based either on the modulation-doped high electron mobility transistor (HEMT) approach, which has high mobility, but is limited in sheet carrier density [1], or the doped channel heterojunction field effect transistor (HFET) structure, which gives increased carrier density at the expense of degraded mobility [2]. We have recently reported [3] on a layer structure which combines the desirable features of these two approaches, and have demonstrated the possibility of obtaining high channel density structures (∼5 × 10 12 carriers cm −2 ) with mobility and saturation drift velocity values comparable with existing devices. This paper provides theoretical support for these observations and discusses the application of the structures to FET devices.…”