Designation:F418–77(Reapproved2002)StandardPracticeforPreparationofSamplesoftheConstantCompositionRegionofEpitaxialGalliumArsenidePhosphideforHallEffectMeasurements1ThisstandardisissuedunderthefixeddesignationF418;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thispracticecoversaproceduretobefollowedtofreetheconstantcompositionregionofepitaxiallygrowngalliumarsenidephosphide,GaAs(1−x)Px,fromthesubstrateandgradedregiononwhichitwasgrowninordertomeasuretheelectricalpropertiesofonlytheconstantcompositionregion,whichistypically30to100µmthick.Italsosetsforthtwoalternativeprocedurestobefollowedtomakeelectricalcontacttothespecimen.1.2ItisintendedthatthispracticebeusedinconjunctionwithTestMethodsF76.1.3ThespecificparameterssetforthinthisrecommendedpracticeareappropriateforGaAs0.62P0.38,buttheycanbeapplied,withchangesinetchtimes,tomaterialwithothercompositions.1.4ThispracticedoesnotdealwithmakingorinterpretingtheHallmeasurementonaspecimenpreparedasdescribedherein,otherthantopointouttheexistenceandpossibleeffectsduetothedistributionofthefreecarriersamongthetwoconductionbandminima.1.5Thispracticecanalsobefollowedinthepreparationofspecimensoftheconstantcompositionregionforlightabsorp-tionmeasurementsorformassoremissionspectrometricanalysis.1.6Thispracticebecomesincreasinglydifficulttoapplyasspecimensbecomethinner.1.7Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.Forhazardstate-ment,seeSection9and11.9.2.4.2.ReferencedDocuments2.1ASTMStandards:2D1125TestMethodsforElectricalConductivityandRe-sistivityofWaterF76TestMethodsforMeasuringResistivityandHallCoefficientandDetermin...
