LOW-TEMPERATURE-GROWN BE-DOPED INALP BAND-OFFSET REDUCTION LAYER TO P-TYPE ZNSE

To solve the difficulty of achieving low resistance ohmic contact to p -type ZnSe, the use of an intermediate p-type InAlP layer to p-type Zn Se as a valence band offset reduction layer is studied by gas source m olecular beam epitaxy. It is found that hole concentrations as high as 2 x 10(18) cm(-3) are easily obtained for p-type InAlP layers grown o n GaAs even at low temperature of 350 degrees C, although a higher Be cell temperature is required than that for a 500 degrees C grown p-typ e InAlP due to the decreased electrical activity of Be in InAlP. Despi te the very high Be concentrations, the Be precipitation/segregation i s not observed. It was difficult to obtain the same hole concentration of InAlP layers grown on ZnSe as that on GaAs. However, the insertion of only several monolayers of GaAs between ZnSe and InAlP makes it po ssible to avoid faceting growth of InAlP and to improve the electrical properties of Be-doped InAlP grown on ZnSe. These results suggest tha t the Be-doped InAlP layer can be used as an intermediate layer to for m the low resistance ohmic contact to p-type ZnSe.