Ge (111) Wafers and Ingots

Ge (111) Wafers and Ingots - Wet Etching

Material Name: Ge (111) wafers and ingots
Recipe No.: 909
Primary Chemical Element in Material: Ge
Sample Type: Wafer
Uses: Etching
Etchant Name: None
Etching Method: Wet etching
Etchant (Electrolyte) Composition: 125 ml 5-10% KOH (NaOH), 10 mg I2.
Procedure (Condition): Time: 5-60 min, temperature: hot.
Note: Ge (111) wafers and ingots. Where an ingot is "as-grown" prior to surface grinding to a specific diameter, growth direction can be observed by the hachure growth meniscus marks (3 in <211> directions at 120°) along the ingot length. If they point upwards, it is toward the seed end; if downward, toward the ingot tail. If needed, this gives a <111>A and <111>B direction. To establish this positive or negative wafer surface direction when wafers are sliced from an ingot ground to specific diameter where these hachure marks are nut present..etch lightly with the solution shown. Observe wafer edges for etched triangles for bulk <110> or <011> directions ... triangle point up or down ... up is positive, seed end of ingot. For <100> oriented ingot growth there are four hachure marks in <110> directions at 90°.
Reference: Perrin Walker, William H Tarn: Handbook of Metal Etchants, CRC Press, Boca Raton, Florida, USA, 1990, p. 573.