REGIon number position material
The REGION line defines material names and/or geometric extents of regions in a mesh. Every element must be defined to be some material.
NUmber = integer NEwnum = integer
NUMBER selects a given region by number. NEWNUM defines this region (or subregion) to have a new region number; this feature is most useful to define nonuniformities in 3D regions (see example below).
position
IX.Low = integer IX.High = integer IY.Low = integer IY.High = integer X.Min = real (default is min(x) in device) X.Max = real (default is max(x) in device) Y.Min = real (default is min(y) in device) Y.Max = real (default is max(y) in device) Z.Min = real (default is min(z) in device) Z.Max = real (default is max(z) in device)
These parameters give a location within a domain where a region is to be defined. IX.LOW, IX.HIGH, IY.LOW and IY.HIGH are the indices of a box in a rectangular mesh. X.MIN, X.MAX, Y.MIN, Y.MAX, Z.MIN, Z.MAX are limits given by physical coordinates. For extents in x and y, one must choose either the index limits or the physical limits; for the z extent, only the physical limits are permitted.
material
NAme or Material = character
SEmiconductor = logical (default is false)
INsulator = logical (default is false)
or
SILicon = logical (default is false)
GAas = logical (default is false)
GErmanium = logical (default is false)
SEmiconductor = logical (default is false)
Oxide or SIO2 = logical (default is false)
NItride or SI3n4 = logical (default is false)
SApphire = logical (default is false)
INsulator = logical (default is false)
The first set of parameters give the accepted way of defining material types in the current version of PADRE. NAME (or MATERIAL) defines the material name for a given region. The name may correspond to a material PADRE knows about (such as "silicon" for Si, "gaas" for GaAs, "germanium" for Ge, "sio2" for SiO2, "si3n4" for nitride, "sapphire", "poly" for polysilicon, "aga45" for AlGaAs [Al/(Al+Ga)=.45], "iga53" for InGaAs [In/(In+Ga)=.53]) or a new material which will be defined on a later MATERIAL line. SEMICONDUCTOR defines the material as a semiconductor, meaning that carrier transport will be explicitly computed within these regions. INSULATOR defines the material as a pure insulator with zero carrier densities; only displacement currents are thus accounted for in these regions.
The second set of (logical) parameters are included for compatibility with older versions. Only one of these parameters can be given. SILICON, GAAS, GERMANIUM and SEMICONDUCTOR define different semiconductors (SEMICONDUCTOR defines a generic type); OXIDE, NITRIDE, SAPPHIRE and INSULATOR are different insulators.
The following defines a semiconductor silicon region extending from nodes 1 to 25 in the x direction and nodes 4 to 20 in the y direction :
REGION NUM=1 IX.LO=1 IX.HI=25 IY.LO=4 IY.HI=20 NAME=SILICON SEMI
Note that region lines are cumulative in effect so that the following defines one insulating oxide region comprised of two separate strips.
REGION NUM=1 IX.LO=4 IX.HI=5 IY.LO=1 IY.HI=20 NAME=OXIDE INS REGION NUM=1 IX.LO=36 IX.HI=37 IY.LO=1 IY.HI=40 NAME=OXIDE INS
Define a region number 1 as a semiconductor material called "base". Redefine that part of the region 1 extending beyond z=8.4 to be region 2 which is given oxide as a material type.
REGION NUM=1 SEMI MATER=base REGION NUM=1 NEW=2 Z.MIN=8.4 INSU NAME=sio2