Influence of Different Gate Biases and Gate Lengths on Parasitic Source Access Resistance in AlGaN/GaN Heterostructure FETs

Effect of Different Gate Lengths on Polarization Coulomb Field Scattering Potential in AlGaN/GaN Heterostructure Field-Effect Transistors

“…R can be determined by the scattering theories of the 2DEG electrons in AlGaN/GaN HFETs 31,38,46–50 .…”

“…In AlGaN/GaN HFETs, the 2DEG electrons can be written as Ψ( x , y , z ) =  A −1/2 ψ ( z )exp( ik x x  +  ik y y ) 31,38,46,48,50 . Here A is the normalization constant, k x , k y refer to the components of k in the x -direction and y -direction, respectively.…”

“…5(b). The polarization charge density under the gate region, labeled as ρ G , can be calculated as following 36–38,41 where e 33 and C 33 are the piezoelectric coefficient and the elastic stiffness tensor of AlGaN, respectively, V GS is the gate-source voltage and d AlGaN is the thickness of the AlGaN barrier layer. The free-contact region cannot be affected by the gate bias, where the polarization charges is still equal to ρ 0 .…”

“…Because the 2DEG electron density under the free-contact region is equal to n 2D0 (here n 2D0 refers to the 2DEG electron density under the gate region corresponding to V GS  = 0 V), n 2D  =  n 2D0 is used in Ψ( x , y , z ). The polarization charges under the free-contact region is ρ 0 , therefore the additional charges can be obtained by 36–38,41 The additional polarization charges Δσ 1 is under the gate region. Based on the obtained Δσ 1 , the PCF scattering potential can be written as 31,37,38,50 If the for the electrons under the gate region is chosen, as shown in Fig.…”

“…The non-uniform distribution of polarization charges can generate the PCF scattering potential. The gate length is relevant with the non-uniform distribution of polarization charges 26,30,35,38 . Hence, the different gate lengths can affect the PCF scattering potential.…”