The dependence of AlN molar fraction of AlGaN in wet etching by using tetramethylammonium hydroxide aqueous solution

Abstract

We investigated the etching rate of the m-plane of AlGaN by wet etching with tetramethylammonium hydroxide aqueous solutions (25 wt%, 85 °C). After dry etching was performed along the m-plane of AlGaN, wet etching was performed to stably form the m-plane facet of AlGaN. Also, the etching rate increases as the increased AlN molar fraction. In the case of forming a heterojunction such as a UV light-emitting diode, by performing wet etching for 5 min, the flat m-plane facets were formed even though there was a large dependence in AlN molar fraction. These facets were almost vertical and flat with respect to the c-plane, so it has the potential for the use as laser mirror. Also, no change in current density-voltage characteristics was confirmed after the wet etching. Therefore, this method is effective for deep UV laser diode fabrication technology on sapphire substrate.

Physical and technological analysis of the AlGaN-based UVC-LED: an extended discussion focused on cubic phase as an alternative for surface disinfection.

“…Once the contact layer has been grown and the n-contact layer is exposed by wet or dry etching techniques [172][173][174], ohmic contacts that provide the correct electron injection to the active region must be deposited. The most used metals are Nickel/Gold (Ni/Au) [139,163,170,175], this is because the Ni work function is greater than the p-contact layer work function, avoiding that a Schottky barrier is generated on the p-type material [176,177] and also it has been reported that as the Ni thickness decreases to around 0.8 nm, the reflectivity augments [178].…”

High Crystallinity and Highly Relaxed Al0.60Ga0.40N Films Using Growth Mode Control Fabricated on a Sputtered AlN Template with High‐Temperature Annealing

“…The excitation power density was determined by measuring the excitation area with a CCD camera and measuring the light intensity with a power meter. The cavity of the photoexcitation laser used the combined combining dry and wet etching method, [44] and the experiment was conducted with the edge surface uncoated. The cavity length was fixed at 300 μm and characterized.…”

Vertical and Lateral Etch Survey of Ferroelectric AlN/Al1−xScxN in Aqueous KOH Solutions

“…Table 1 summarizes selected studies on the dry etch rates of AlN/Al 1−x Sc x N: Compared to dry etching, wet etching can be rather advantageous owing to its less expensive tooling. Common etchants include tetramethylammonium hydroxide (TMAH) [19][20][21], phosphoric acid (H 3 PO 4 ) [22,23] or phosphoric acid-based solution [21] (PWS, containing 80% H 3 PO 4 , 16% H 2 O and 4% HNO 3 ), potassium hydroxide (KOH) [22,24,25] and AZ400K Developer (contain 10 wt% of KOH) [26]. Among them, we found KOH to be rather attractive due to its availability and non-toxicity with a relatively high etch rate and high etch selectivity to silicon nitride (SiN x ).…”