Growth of AlInAs/GaInAs MODFET structures on InP substrates by molecular beam epitaxy (MBE)

Abstract

We have estensively studied the relationship between gronlli conditions and electron transfer properties during growth o f A l l n A s~G a l n . 4~ 1 lnP MODFET structures by MBE. The structure's quality can be successfully controlled b j controlling gowth surface recons:ruction status via observation of RHEED patterns and grouth phase diagram of G~,471i~o,5jAs layers. For lattice matched cliannel, the optimal spacer thickness \\*as determined as 40 A aRer consid-ring scattering and electron density dropping in channel as well as Si planer doped layer's parallel conductance effect. and ! I ;~~~ and 2DEG density are typically more thin 10,000 cm' :v.s and 2.5E12cm", rcspectivelj. For pseudomorphic channel, \ve have compared resuits of tu0 type distributions of I n composition in GalnAs pseudoniorpliic channel, i.e. rectmgular 'A' typc and .V' type, and esperimcim demonstrated that .V. h p c has advantapes. After optimization o f growth conditions. our best MODI:ET structure result reaches nearly jiTk;< --I ;OOOcm'/v.s. ~D E G 2 2 .~1 : . I ?mi" . I.lntroduction Modulation doped field erect transis:or (JlODlLll babed on AllnAs/<;alnAs t' InP IleterostrwturCs g r o w by MBE has recently become an important cacdidate for low-noise applications at microwave and rnillimetrr frequencies [I]. this strongly stiniulatrs the desire of understanding MBE technique in MODFET structures grotbqh on lriP substrates. l h r basic properties o!' rMODFET's structures are presented by ZDEG densit> n, and it's mobility p, and usually the n, arid it's mobility p are controlled sevcrcly by growtli paranieteri. such as growth temperature. latticc matching status, grotrth surface status. structure designs and so on [?I. In this paper. we report the growth parameter's influences on ?DEG transfcr properties o i AllnAs:GalnAs MODI.'E'l Structure. especially thc channel derign's effect oil the 2DEG's nobility. 2.Experirnen t Our MBE sysieni i.; Riber 32. Fe-doped InP (100) subwatsi arc "epi-ready" grade. All solid state sources' purity are 7X. and Si i s n type dopant (6s,-5E12cm-'). Gronth rate is 6000 Arbh, growth teniperature i s nionitored b\ Irson optical pyrometer and deterniincd as 500% according to our MBE growth RMEED phase diagriini of Giid,7h033As layer on lnP substrate, Fig. I. l h e Aloislno j+'GalnAs MODFET Structures are shown in I-.is.l. Before grorirh. heat InP substrate to 510.C: in growth chamber for ten mintitel under As, BEP 9E-7 torr, and the stirfacc rcconstrilciion keeps in ( 3 x 1 1 status. Figl. Then lili the temp?raturc IO about 540-550.C for a short iiine jxst enough to see (4.1) status via RllEED ob;cwation [.3.41. This means substrate surface is clean and oside la!er \vas taken OK. Then I o w r the substiate temperawre immediatel! to iOO'C, AloJslno j2.4s buffer layer grouing Stan.