Comparative Studies on InAlAs/InGaAs MOS-MHEMTs with Different Compressive/Tensile-Strained Channel Structures

Abstract

Comparative studies of double δ-doped InAlAs/InGaAs metal-oxide-semiconductor metamorphic high electron mobility transistors (MOS-MHEMTs) with different compressive-strained and tensile-strained channel structures have been made. In addition to the strain engineering of the heterostructure, the MOS-gate design is also integrated by using the cost-effective H 2 O 2 oxidization technique. The tensile (compressive)-strained channel is devised by the In 0.52 Al 0.48 As/In 0.41 Ga 0.59 As (In 0.52 Al 0.48 As/In 0.63 Ga 0.37 As) heterostructure. Device characteristics with respect to different channel structures are physically studied. The impact-ionizationrelated kink effects in MHEMTs are significantly suppressed by the MOS-gate. Atomic force microscopy (AFM) and low-frequency noise (LFN) analysis were used to study the surface roughness and interface quality. As compared to the compressive-strained MOS-MHEMT and conventional Schottky-gate devices, the present tensile-strained MOS-MHEMT design has demonstrated improved transconductance gain (g m ), current drive, intrinsic voltage gain (A V ), and power performance. InAlAs/InGaAs MHEMTs have demonstrated advantages of large wafer-size and high electron mobility with respect to pseudomorphic high electron mobility transistors (pHEMTs) 1,2 and latticematched HEMTs on InP substrates. 3,4 It is because that the In-rich InGaAs channel can be grown on a robust GaAs substrate by the graded In x Al 1-x As metamorphic buffer (MB) design. Nevertheless, the impact-ionization-related kink effect 5 usually occurs in MHEMTs. This would seriously degrade gate leakage current, static power dissipation, and power-added efficiency (P.A.E.). Studies of strain engineering in the III-V research field have been made. 6,7 Channel engineering has been applied to form tensile-strained or compressivestrained HEMTs.8 The tensile-strained channel design has also been successfully used to effectively improve the carrier mobility in Sibased devices. A simple and cost-effective H 2 O 2 oxidization technique has been proposed in our previous work. 24 Therefore, this work investigates double δ-doped InAlAs/InGaAs MOS-MHEMTs based on strain engineering of the AlGaAs/InGaAs heterostructure and MOS-gate design by using the cost-effective H 2 O 2 oxidization method. Surface and interfacial property of the MOS-gate structure are studied by using AFM and LFN spectra. Device characteristics with respect to different strain mechanisms and Schottky/MOS-gate structures are physically investigated. Material Growth and Device FabricationThe schematic device structures of the studied InAlAs/InGaAs MHEMTs and MOS-MHEMTs grown by a MBE system are shown in Figs. 1a-1d. Upon the semi-insulating (S.I.) GaAs substrate, the epitaxial layers consist of a 5000-Å In x Al 1-x As MB layer, a 1500-Å undoped In 0.52 Al 0.48 As buffer, a Si δ-doped (n + = where a sc /a ch are the lattice constants of the Schottky-contact layer/channel. The lattice constant of the In x Ga 1-x As compound can be approximated by 25 a I nGa As = ...

Effect of Strain on Electron Transport and Quantum Lifetimes in InxGa1−xAs/In0.52Al0.48As Modulation Doped Double Quantum Well‐Based High Electron Mobility Transistor Structures

“…Numerous efforts have been made to grow In x Ga 1Àx As as the channel over In 0.52 Al 0.48 As on InP or GaAs substrate. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] The change in x produces lattice-matched (x = 0.53) as well as strained (x 6 ¼ 0.53) heterostructures. Efforts are also made to study different scattering mechanisms that influence transport properties like electron mobility (μ), transport (τ t ), and quantum (τ q ) lifetime in lattice-matched as well as strained InGaAs/InAlAs quantum well (QW) structures.…”

“…[17] In addition to the aforementioned works, very few attempts have also been made for strain compensation, which improved structural and electrical properties in InGaAs/InAlAs HEMT structures. [6,9,16] The dominance of either the small or large angle scattering effects can be estimated by the transport (τ t ), and quantum (τ q ) lifetime. The single particle quantum lifetime τ q considers both small-and large-angle (θ) scatterings.…”

“…The indium composition in the barriers (In 0.52 Al 0.48 As) in all the structures is 0.52. The in-plane strain of the proposed strained structures can be expressed as: [16] ε k¼ a barrier Àa well a well (1) Here, a barrier and a well are the lattice constants of the barrier and well, respectively. The design parameters of the barrier layers, i.e., In 0.52 Al 0.48 As, and different well layers, i.e., In 0.53 Ga 0.47 As, In 0.41 Ga 0.59 As, and In 0.75 Ga 0.25 As are given in Table 1.…”

“…[ 17 ] In addition to the aforementioned works, very few attempts have also been made for strain compensation, which improved structural and electrical properties in InGaAs/InAlAs HEMT structures. [ 6,9,16 ]…”

Al2O3-Passivated Graded-Barrier AlxGa1-xN/AlN/GaN/Si Heterostructure Field-Effect Transistor by Hydrogen Peroxide Oxidization Method

“…In comparison, an Al 0.26 Ga 0.74 N conventional barrier (CB) with equivalent Al-ratio to that of the Al x Ga 1-x N (x = 0.22∼0.3) graded-barrier (GB) was devised. Besides, surface passivation of Al 2 O 3 was formed within the gate-drain/source regions of the GB-HFET by using the hydrogen peroxide (H 2 O 2 ) oxidization [3][4][5][6][7] method. As compared to other oxidization systems, 8,9 the H 2 O 2 oxidization is cost effective and compatible to device fabrication processing.…”