Characterization of Hg0.7Cd0.3Te n- on p-type structures obtained by reactive ion etching induced p- to n conversion

This paper presents transport measurements on both vacancy doped and gold d oped Hg0.7Cd0.3Te p-type epilayers grown by liquid phase epitaxy (LPE), wit h N-A = 2 x 10(16) cm(-3), in which a thin 2 mu m surface layer has been co nverted to n-type by a short reactive ion etching (RIE) process. Hall and r esistivity measurements were performed on the n-on-p structures in van der Pauw configuration for the temperature range from 30 K to 400 K and magneti c field range up to 12 T. The experimental Hall coefficient and resistivity data has been analyzed using the quantitative mobility spectrum analysis p rocedure to extract the transport properties of each individual carrier con tributing to the total conduction process. In both samples three distinct c arrier species have been identified. For 77 K, the individual carrier speci es exhibited the following properties for the vacancy and Au-doped samples, respectively, holes associated with the unconverted p-type epilayer with p approximate to 2 x 10(16) cm(-3), mu approximate to 350 cm(2)V(-1)s(-1), a nd p approximate to 6 x 10(15) cm(-3), mu approximate to 400 cm(2)V(-1)s(-1 ); bulk electrons associated with the RIE converted region with n approxima te to 3 x 10(15) cm(-3), mu = 4 x 10(4) cm(2)V(-1)s(-1), and n approximate to 1.5 x 10(15) cm(-3), mu approximate to 6 x 10(4) cm(2)V(-1)s(-1); and su rface electrons (2D concentration) n approximate to 9 x 10(12) cm(-2) and n approximate to 1 x 10(13) cm-2, With mobility in the range 1.5 x 10(3) cm( 2)V(-1)s(-1) to 1.5 x 10(4) cm(2)V(-1)s(-1) in both samples. The high mobil ity of bulk electrons in the RIE converted n-layer indicates that a diffusi on process rather than damage induced conversion is responsible for the p-t o-n conversion deep in the bulk. On the other hand, these results indicate that the surface electron mobility is affected by RIE induced damage in a v ery thin layer at the HgCdTe surface.