Method for oxidizing a substrate surface using oxygen
A method for treating a compound semiconductor substrate, in which method in vacuum conditions a surface of an In-containing III-As, III-Sb or III-P substrate is cleaned from amorphous native oxides and after that the cleaned substrate is heated to a temperature of about 250-550° C. and oxidized by introducing oxygen gas onto the surface of the substrate. The invention relates also to a compound semiconductor substrate, and the use of the substrate in a structure of a transistor such as MOSFET.
1. A method for producing a crystalline oxide layer on an In-containing III-As, III-Sb or III-P compound semiconductor substrate, comprising in vacuum conditions
providing an In-containing III-As, III-Sb or III-P substrate having a substrate surface which is clean from amorphous native oxides, and
heating said substrate having a clean surface to a temperature of about 250-550° C., and oxidizing it at said temperature of about 250-550° C. by introducing oxygen gas onto the surface of the substrate,
wherein said method produces a compound semiconductor substrate comprising at least
an In-containing III-As, III-Sb or III-P base material having a first side and a second side, and
a crystalline (3×1)-O, c(4×2)-O, (1×2)-O, (2×3)-O, (3×1)-SnO, (3×3)-SnO, or (1×1)-SnO oxide layer being formed on at least a part of the first side of the base material.
2. The method according to claim 1 , wherein the In-containing III-As, III-Sb or III-P substrate is made of InAs, InSb, InP, InGaAs or InGaSb.
3. The method according to claim 1 , wherein the substrate is cleaned by argon-ion sputtering and post heating in ultra-high-vacuum (UHV) conditions at least to 400° C., or by pure heating in UHV at around 400-550° C.
4. The method according to claim 1 , wherein the cleaned substrate is covered by a tin (Sn) layer.
5. The method according to claim 1 , wherein the cleaned In-containing III-As substrate is heated to a temperature of about 340-400° C.
6. The method according to claim 1 , wherein the cleaned In-containing III-Sb substrate is heated to a temperature of about 340-450° C.
7. The method according to claim 1 , wherein the cleaned In-containing III-P substrate is heated to a temperature of about 450-500° C.
8. The method according to claim 1 , wherein the heating and the oxidation of the substrate are carried out simultaneously.
9. The method according to claim 1 , wherein the substrate is oxidized for 15 to 45 minutes.
10. The method according to claim 9 , wherein the substrate is oxidized for 15 to 30 minutes.
11. The method according to claim 1 , wherein the oxygen gas pressure is between 5×10 −7 and 5×10 −5 mbar.