Improved In0.45Al0.55As/In0.45Ga0.55As/In0.65Ga0.35As Inverse Composite Channel Metamorphic High Electron Mobility Transistor

Self Cite

InP-based InAlAs/In x Ga 1−x As/InP high-electron-mobility transistors (HEMTs) with a symmetrically graded channel (SGC-HEMT) and an inversely graded channel (IGC-HEMT) were fabricated and studied. The SGC-HEMT exhibits better Hall, dc and RF characteristics than the IGC-HEMT because there are more electrons accumulated in the symmetrically graded channel. However, the IGC-HEMT has better thermal stability than the SGC-HEMT because the former has higher bandgap discontinuity at the channel/buffer heterojunction and less Coulomb scattering from a δ-doped layer. Furthermore, the IGC-HEMT sustains larger output power than the SGC-HEMT attributed to better breakdown characteristics. Therefore, HEMTs with the symmetrically graded and an inversely graded channel are suitable for high-speed and high-power applications, respectively.

Section: Introductionmentioning

confidence: 99%

Comparative study of In_0.52Al_0.48As/In_xGa₁₋_xAs/InP high-electron-mobility transistors with a symmetrically graded and an inversely graded channel

Huang

Hsu

Lin

et al. 2006

Self Cite

“…Due to the high low-field electron mobility, high peak electron velocity, large conduction-band discontinuity ( E C ) between Schottky and channel layers, and high sheetcarrier density, InAlAs/InGaAs high electron mobility transistors (HEMTs) lattice matched to InP substrates have shown better microwave and low-noise characteristics than AlGaAs/InGaAs pseudomorphic high electron mobility transistors (PHEMTs) on GaAs substrates [1][2][3][4]. Since InP substrates generally suffer from mechanical fragility, wafer size and high cost, the GaAs substrate is more suitable for manufacturing large-scale millimetre-wave integrated circuit (MMIC) [5].…”

Section: Introductionmentioning

confidence: 99%

Temperature dependences of an In_0.46Ga_0.54As/In_0.42Al_0.58As based metamorphic high electron mobility transistor (MHEMT)

Chen

Lai

Lour

et al. 2006

In this paper, an interesting thermally stable In 0.42 Al 0.58 As/In 0.46 Ga 0.54 As metamorphic high electron mobility transistor (MHEMT) is fabricated and investigated. Good dc and RF characteristics are obtained by precisely depositing gold (Au) upon the In 0.42 Al 0.58 As barrier layer as the Schottky contact metal. For a MHEMT with gate dimensions of 1 × 100 µm 2 , high gate-drain breakdown voltage, high turn-on voltage, low gate leakage current density, high maximum transconductance with broad operating regime and low output conductance are obtained even at ambient temperatures up to 510 K (240 • C). The studied device also shows a very good microwave performance at room temperature. Moreover, the relatively low variations of the device performance are achieved over a wide temperature range (from 300 to 510 K). Therefore, the studied device has a good thermally stable performance that is suitable for high-speed and high-power electronic applications.

“…Figure 5(a) shows the microwave characteristics. The MDDFET exhibits a cut-off frequency (f T ) of 45 GHz and a maximum oscillation frequency (f max ) of 125 GHz as biased at V DS = 2.5 V and V GS = −1.25 V. The RF performances of the proposed device are better than those of most GaAsbased DCFETs and DDCFETs, and are comparable to those of some reported MHEMTs due to the high mobility of the In-rich channel [2,5,7,13]. As compared to conventional GaAs-based InGaAs/GaAs/InGaAs DCFETs or DDCFETs, the degradation of microwave performances due to the high impurity scattering is compensated by the high-speed In-rich channel in the MDDFET.…”

Section: Resultsmentioning

confidence: 52%

A metamorphic heterostructure field-effect transistor with a double delta-doped channel

Huang

Hsu

Lin

et al. 2007

Self Cite

This study presents a metamorphic heterostructure field-effect transistor with a double δ-doped channel (MDDFET). The coupled δ-doped In 0.5 Ga 0.5 As/δ + /In 0.5 Ga 0.5 As/In 0.6 Ga 0.4 As/In 0.5 Ga 0.5 As/δ + /In 0.5 Ga 0.5 As channel demonstrates high carrier concentration and high mobility due to the good carrier confinement of the δ-doped design and the coupled wavefunction in the undoped In-rich channel. Experimental results indicate that the MDDFET with the gate dimension of 0.65 × 100 µm 2 exhibits a maximum extrinsic transconductance of 320 mS mm −1 , a saturated drain current density of 566 mA mm −1 at V GS = 0 V, a cut-off frequency of 45 GHz, a maximum oscillation frequency of 125 GHz and a saturated power of 15.9 dBm at 5.8 GHz. These results demonstrate that this studied device is appropriate for high-frequency and high-power applications.